Respiratory pressure therapy system

ABSTRACT

The present technology is directed to a respiratory pressure therapy system, that includes a plenum chamber pressurisable to a therapeutic pressure above ambient air pressure, a seal-forming structure to form a seal with an entrance to the patient&#39;s airways to maintain said therapeutic pressure in the plenum chamber throughout the patient&#39;s respiratory cycle in use, a positioning and stabilising structure constructed and arranged to provide an elastic force to hold the seal-forming structure in a therapeutically effective position on the patient&#39;s head, a blower configured to generate the flow of air and pressurise the plenum chamber to the therapeutic pressure, the blower having a motor, the blower being connected to the plenum chamber such that the blower is suspended from the patient&#39;s head and the axis of rotation of the motor is perpendicular to the patient&#39;s sagittal plane, and a power supply configured to provide electrical power to the blower.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Australian ProvisionalApplication No. AU 2016902914, filed Jul. 25, 2016, AustralianProvisional Application No. 2016904093, filed Oct. 11, 2016, U.S.Provisional Application No. 62/458,862, filed Feb. 14, 2017, and U.S.Provisional Application No. 62/512,445 filed by May 30, 2017, each ofwhich is incorporated herein by reference in its entirety.

BACKGROUND OF THE TECHNOLOGY 2.1 Field of the Technology

The present technology relates to one or more of the detection,diagnosis, treatment, prevention and amelioration of respiratory-relateddisorders. The present technology also relates to medical devices orapparatus, and their use.

2.2 Description of the Related Art

2.2.1 Human Respiratory System and its Disorders

The respiratory system of the body facilitates gas exchange. The noseand mouth form the entrance to the airways of a patient.

The airways include a series of branching tubes, which become narrower,shorter and more numerous as they penetrate deeper into the lung. Theprime function of the lung is gas exchange, allowing oxygen to move fromthe inhaled air into the venous blood and carbon dioxide to move in theopposite direction. The trachea divides into right and left mainbronchi, which further divide eventually into terminal bronchioles. Thebronchi make up the conducting airways, and do not take part in gasexchange. Further divisions of the airways lead to the respiratorybronchioles, and eventually to the alveoli. The alveolated region of thelung is where the gas exchange takes place, and is referred to as therespiratory zone. See “Respiratory Physiology”, by John B. West,Lippincott Williams & Wilkins, 9th edition published 2012.

A range of respiratory disorders exist. Certain disorders may becharacterised by particular events, e.g. apneas, hypopneas, andhyperpneas.

Examples of respiratory disorders include Obstructive Sleep Apnea (OSA),Cheyne-Stokes Respiration (CSR), respiratory insufficiency, ObesityHyperventilation Syndrome (OHS), Chronic Obstructive Pulmonary Disease(COPD), Neuromuscular Disease (NMD) and Chest wall disorders.

2.2.2 Therapy

Various therapies, such as Continuous Positive Airway Pressure (CPAP)therapy, Non-invasive ventilation (NIV) and Invasive ventilation (IV)have been used to treat one or more of the above respiratory disorders.

2.2.3 Treatment Systems

These therapies may be provided by a treatment system or device. Suchsystems and devices may also be used to diagnose a condition withouttreating it.

A treatment system may comprise a Respiratory Pressure Therapy Device(RPT device), an air circuit, a humidifier, a patient interface, anddata management.

Another form of treatment system is a mandibular repositioning device.

2.2.3.1 Patient Interface

A patient interface may be used to interface respiratory equipment toits wearer, for example by providing a flow of air to an entrance to theairways. The flow of air may be provided via a mask to the nose and/ormouth, a tube to the mouth or a tracheostomy tube to the trachea of apatient. Depending upon the therapy to be applied, the patient interfacemay form a seal, e.g., with a region of the patient's face, tofacilitate the delivery of gas at a pressure at sufficient variance withambient pressure to effect therapy, e.g., at a positive pressure ofabout 10 cmH₂O relative to ambient pressure. For other forms of therapy,such as the delivery of oxygen, the patient interface may not include aseal sufficient to facilitate delivery to the airways of a supply of gasat a positive pressure of about 10 cmH₂O.

2.2.3.2 Respiratory Pressure Therapy (RPT) Device

A respiratory pressure therapy (RPT) device may be used to deliver oneor more of a number of therapies described above, such as by generatinga flow of air for delivery to an entrance to the airways. The flow ofair may be pressurised. Examples of RPT devices include a CPAP deviceand a ventilator.

Air pressure generators are known in a range of applications, e.g.industrial-scale ventilation systems. However, air pressure generatorsfor medical applications have particular requirements not fulfilled bymore generalised air pressure generators, such as the reliability, sizeand weight requirements of medical devices. In addition, even devicesdesigned for medical treatment may suffer from shortcomings, pertainingto one or more of: comfort, noise, ease of use, efficacy, size, weight,manufacturability, cost, and reliability.

An example of the special requirements of certain RPT devices isacoustic noise.

Table of noise output levels of prior RPT devices (one specimen only,measured using test method specified in ISO 3744 in CPAP mode at 10cmH₂O).

A-weighted sound Year RPT Device name power level dB(A) (approx.)C-Series Tango ™ 31.9 2007 C-Series Tango ™ with Humidifier 33.1 2007 S8Escape ™ II 30.5 2005 S8 Escape ™ II with H4i ™ Humidifier 31.1 2005 S9AutoSet ™ 26.5 2010 S9 AutoSet ™ with H5i Humidifier 28.6 2010

One known RPT device used for treating sleep disordered breathing is theS9 Sleep Therapy System, manufactured by ResMed Limited. Another exampleof an RPT device is a ventilator. Ventilators such as the ResMedStellar™ Series of Adult and Paediatric Ventilators may provide supportfor invasive and non-invasive non-dependent ventilation for a range ofpatients for treating a number of conditions such as but not limited toNMD, OHS and COPD.

The ResMed Elisée™ 150 ventilator and ResMed VS III™ ventilator mayprovide support for invasive and non-invasive dependent ventilationsuitable for adult or paediatric patients for treating a number ofconditions. These ventilators provide volumetric and barometricventilation modes with a single or double limb circuit. RPT devicestypically comprise a pressure generator, such as a motor-driven bloweror a compressed gas reservoir, and are configured to supply a flow ofair to the airway of a patient. In some cases, the flow of air may besupplied to the airway of the patient at positive pressure. The outletof the RPT device is connected via an air circuit to a patient interfacesuch as those described above.

The designer of a device may be presented with an infinite number ofchoices to make. Design criteria often conflict, meaning that certaindesign choices are far from routine or inevitable. Furthermore, thecomfort and efficacy of certain aspects may be highly sensitive tosmall, subtle changes in one or more parameters.

2.2.3.3 Humidifier

Delivery of a flow of air without humidification may cause drying ofairways. The use of a humidifier with an RPT device and the patientinterface produces humidified gas that minimizes drying of the nasalmucosa and increases patient airway comfort. In addition in coolerclimates, warm air applied generally to the face area in and about thepatient interface is more comfortable than cold air.

2.2.3.4 Data Management

There may be clinical reasons to obtain data to determine whether thepatient prescribed with respiratory therapy has been “compliant”, e.g.that the patient has used their RPT device according to certain a“compliance rule”. One example of a compliance rule for CPAP therapy isthat a patient, in order to be deemed compliant, is required to use theRPT device for at least four hours a night for at least 21 of 30consecutive days. In order to determine a patient's compliance, aprovider of the RPT device, such as a health care provider, may manuallyobtain data describing the patient's therapy using the RPT device,calculate the usage over a predetermined time period, and compare withthe compliance rule. Once the health care provider has determined thatthe patient has used their RPT device according to the compliance rule,the health care provider may notify a third party that the patient iscompliant.

There may be other aspects of a patient's therapy that would benefitfrom communication of therapy data to a third party or external system.

Existing processes to communicate and manage such data can be one ormore of costly, time-consuming, and error-prone.

2.2.3.5 Vent Technologies

Some forms of treatment systems may include a vent to allow the washoutof exhaled carbon dioxide. The vent may allow a flow of gas from aninterior space of a patient interface, e.g., the plenum chamber, to anexterior of the patient interface, e.g., to ambient.

3. BRIEF SUMMARY OF THE TECHNOLOGY

The present technology is directed towards providing medical devicesused in the diagnosis, amelioration, treatment, or prevention ofrespiratory disorders having one or more of improved comfort, cost,efficacy, ease of use and manufacturability.

A first aspect of the present technology relates to an apparatus used inthe diagnosis, amelioration, treatment or prevention of a respiratorydisorder.

Another aspect of the present technology relates to methods used in thediagnosis, amelioration, treatment or prevention of a respiratorydisorder.

An aspect of certain forms of the present technology is to providemethods and/or apparatus that improve the compliance of patients withrespiratory therapy.

An aspect of certain forms of the present technology is a medical devicethat is easy to use, e.g. by a person who does not have medicaltraining, by a person who has limited dexterity, vision or by a personwith limited experience in using this type of medical device.

An aspect of one form of the present technology is a portable RPT devicethat may be carried by a person, e.g., around the home of the person.

An aspect of one form of the present technology is a patient interfacethat may be washed in a home of a patient, e.g., in soapy water, withoutrequiring specialised cleaning equipment. An aspect of one form of thepresent technology is a humidifier tank that may be washed in a home ofa patient, e.g., in soapy water, without requiring specialised cleaningequipment.

The methods, systems, devices and apparatus described herein can provideimproved functioning in a processor, such as of a processor of aspecific purpose computer, respiratory monitor and/or a respiratorytherapy apparatus. Moreover, the described methods, systems, devices andapparatus can provide improvements in the technological field ofautomated management, monitoring and/or treatment of respiratoryconditions, including, for example, sleep disordered breathing.

Another aspect of the present technology is directed to a respiratorypressure therapy (RPT) system that includes a patient interface and apressure generator, wherein the pressure generator is supported on thepatient's head in use by the patient interface.

Another aspect of the present technology is directed to a pressuregenerator having a single motor and a single shaft, each end of theshaft positioned at a corresponding end of the motor. The pressuregenerator may further comprise at least one compression stage associatedwith each end of the shaft, each compression stage including an impellerand a stator.

Another aspect of the present technology is directed to a blower thatincludes an blower inlet at each lateral and at least one blower outletpositioned between the blower inlets, the blower outlet extendingannularly around at least a portion of the circumference of the blower.

Another aspect of the present technology is directed to a respiratorypressure therapy (RPT) system. The RPT system comprises: a plenumchamber pressurisable to a therapeutic pressure of at least 6 cmH2Oabove ambient air pressure; a seal-forming structure constructed andarranged to form a seal with a region of the patient's face at orsurrounding an entrance to the patient's airways such that a flow of gasat said therapeutic pressure is delivered to at least the entrance tothe patient's nares, the seal-forming structure constructed and arrangedto maintain said therapeutic pressure in the plenum chamber throughoutthe patient's respiratory cycle in use; a positioning and stabilisingstructure constructed and arranged to provide an elastic force to holdthe seal-forming structure in a therapeutically effective position onthe patient's head, the positioning and stabilising structure comprisinga tie, a lateral portion of the tie being constructed and arranged tooverlie a region of the patient's head superior to the otobasionsuperior in use, and a superior portion of the tie being constructed andarranged to overlie a region of the patient's head in a region of theparietal bone in use, wherein the positioning and stabilising structurehas a non-rigid decoupling portion; a blower configured to generate theflow of gas and pressurise the plenum chamber to the therapeuticpressure, the blower having a motor, the blower being connected to theplenum chamber such that in use the blower is suspended from thepatient's head and an axis of rotation of the motor is generallyperpendicular to the patient's sagittal plane; and a power supplyconfigured to provide electrical power to the blower.

In examples, (a) the seal-forming structure may be constructed such thatno part thereof enters the patient's mouth in use, (b) the seal-formingstructure may not extend internally of the patient's airways, (c) theplenum chamber may not cover the eyes in use, (d) the blower may becontained at least partially within the plenum chamber, (e) the plenumchamber may comprise at least one housing portion, (e) the plenumchamber may comprise at least two housing portions that are at leastpartially separable to allow the blower to be removed from the plenumchamber, (f) the at least two housing portions may be joined at one sidein a clamshell arrangement to allow the plenum chamber to be opened andclosed, (g) the RPT system may comprise a sealing structure between theat least two housing portions, (h) the plenum chamber may include atleast one attachment structure to attach the positioning and stabilisingstructure to secure the RPT system to the patient's head in use, (i) theplenum chamber may comprise a plenum chamber outlet through which theflow of gas passes from the blower to at least the entrance to thepatient's nares in use, (j) the seal-forming structure may be connectedto the plenum chamber at the plenum chamber outlet, (k) the plenumchamber may comprise a port that is configured to be connected to atleast one of a pressure transducer and a supplemental gas source, (l)the seal-forming structure may comprise: a pair of nasal puffs, or nasalpillows, each nasal puff or nasal pillow being constructed and arrangedto form a seal with a respective naris of the nose of the patient; aseal-forming structure that forms a seal in use on a nose bridge regionor on a nose-ridge region of the patient's face and that forms a seal inuse on an upper lip region of the patient's face; or a seal-formingstructure that forms a seal in use on a nose bridge region or on anose-ridge region of the patient's face and that forms a seal in use ona chin-region of the patient's face, (m) the RPT system may comprise aheat and moisture exchanger (HME) within the plenum chamber that ispositioned in the flow of gas and downstream of the blower, (n) the RPTsystem may not include a vent such that in use the patient exhalesthrough the blower in opposition to the flow of gas and the patient'sexhalate exits the RPT system through an inlet of the blower, (o) thepower supply may comprise a battery, the battery may comprise at leastone electrochemical cell, (p) the battery may be supported by thepositioning and stabilising structure on a region of the patient's headadjacent to the parietal bone, (q) the battery may be contained withinthe positioning and stabilising structure, (r) the RPT system maycomprise at least one wire supported by the positioning and stabilisingstructure, the at least one wire providing electrical communicationbetween the blower and the battery, (s) the at least one wire may becontained within the lateral portion of the positioning and stabilisingstructure, (t) the RPT system may comprise at least one tube in fluidcommunication with the plenum chamber at a first end and a pressuretransducer at a second end, the at least one tube contained within thelateral portion of the positioning and stabilising structure, (u) theseal-forming structure may comprise an elastically deformable materialthat is less rigid than the plenum chamber, and a portion of theseal-forming structure may substantially enclose the plenum chamber andthe blower while allowing at least an inlet of the blower to remainexposed, (v) the seal-forming structure may be shaped and dimensionedand the elastically deformable material of the seal-forming structuremay be selected to at least partially isolate the patient's head fromvibration and dampen sound generated by the blower in use, (w) the RPTsystem may comprise a cover comprising an elastically deformablematerial that is less rigid than the plenum chamber that substantiallyencloses the plenum chamber and the blower while allowing at least aninlet of the blower to remain exposed, (x) the cover may be shaped anddimensioned and the elastically deformable material of the cover may beselected to at least partially isolate the patient's head from vibrationand dampen sound generated by the blower in use, (y) the RPT system maycomprise a control system to control the blower in use, (z) the controlsystem may comprise a flexible printed circuit board assembly (PCBA),the PCBA comprising a microprocessor, (aa) the microprocessor may beprogrammed to perform at least one of closed-loop pressure control basedon sensed pressure data, flow rate estimation, and automaticallyadjusting expiration pressure relief, and/or (bb) the control system maycomprise a drive circuit to control the power supply separately from theblower.

Another aspect of the present technology is directed to a blower for arespiratory pressure therapy (RPT) system, the blower being configuredto generate a flow of gas at a therapeutic pressure of at least 6 cmH2Oabove ambient air pressure. The blower may comprise: a motor having afirst end and a second end; a shaft having a first shaft end extendingfrom the first end of the motor and a second shaft end extending fromthe second end of the motor; a first impeller and a second impellerarranged in series on each of the first shaft end and the second shaftend such that both first impellers and both second impellers are drivensimultaneously by the motor; a first stator corresponding to each of thefirst end of the motor and the second end of the motor, the first statorpositioned downstream of the first impeller and upstream of the secondimpeller along the flow of gas generated by the blower in use; a secondstator corresponding to each of the first end of the motor and thesecond end of the motor, the second stator positioned downstream of thesecond impeller along the flow of gas generated by the blower in use; anend cap shaped and dimensioned to at least partially enclose each firstimpeller and at least partially define a blower inlet; a blower outletpositioned downstream of each second stator; and a flow path for theflow of gas passing from each blower inlet, past each first impeller,through each first stator, past each second impeller, through eachsecond stator, and out each blower outlet.

In examples, (a) each first stator may comprise a plurality of firststator vanes to direct the flow of gas from the first impeller to thefirst stator opening in a radial direction, reduce the velocity of theflow of gas from the first impeller, and increase the pressure of theflow of gas from the first impeller, (b) the plurality of first statorvanes may comprise extended first stator vanes and short first statorvanes, the extended first stator vanes may extend further radiallyinward than the short first stator vanes, and the extended first statorvanes and the short first stator vanes may alternate circumferentiallyaround the first stator, (c) the extended first stator vanes and theshort first stator vanes each may comprise a curved portion that isswept backwards relative to the direction of rotation of thecorresponding first impeller, and the extended first stator vanes andthe short first stator vanes each may comprise a straight portion thatextends radially inward from the curved portion, the straight portion ofeach of the extended first stator vanes may extend radially inwardfurther than the straight portion of each of the short first statorvanes, (d) each first stator may comprise a first stator openingdownstream of the plurality of first stator vanes to direct the flow ofgas to the second impeller, (e) each first stator may comprise a firststator upper shroud to direct the flow of gas from the first impeller tothe first stator opening in an axial direction, the corresponding firstimpeller positioned adjacent to the first stator upper shroud, (f) eachfirst stator may comprise a first stator housing, and each secondimpeller and each second stator may be at least partially containedwithin the corresponding first stator housing such that the flow of gastravelling along the flow path past the second impeller and through thesecond stator also passes through the first stator housing, (g) eachfirst stator housing may at least partially define the correspondingblower outlet, (h) each first stator housing may comprise a mountingstructure to connect the blower to the RPT system, (i) each mountingstructure may comprise a pair of mounting rails extending around theouter circumference of each first stator housing, (j) each end cap maybe constructed to dampen sound and vibration, (k) each end cap maycomprise a rigid material to provide structural integrity and a lessrigid, elastically deformable material overmolded to the rigid materialto dampen sound and vibration, (l) each first impeller and each secondimpeller may comprise an impeller hub, impeller vanes extending radiallyfrom the impeller hub, and an impeller shroud, (m) each of the impellervanes may comprise a first impeller vane portion that extends only in aradial direction and a second impeller vane portion that extends in aradial and axial direction, (n) the first impeller vane portion of eachof the impeller vanes of each first impeller and each second impellermay have a constant cross-section and may be radially inward relative tothe second impeller vane portion, the second impeller vane portion mayhave a variable cross-section and may be radially outward relative tothe first impeller vane portion, and the constant cross-section of thefirst impeller vane portion may be thinner than the variablecross-section of the second impeller vane portion, (o) each impellershroud may comprise a first impeller shroud portion that extends only ina radial direction and a second impeller shroud portion that extends ina radial and axial direction, (p) the impeller vanes of each firstimpeller and each second impeller may be swept forward relative to thedirection of rotation during operation, (q) each second stator maycomprise a top ring, a base ring, and a plurality of second stator vanesthat join the top ring and the base ring, and the plurality of secondstator vanes may direct the flow of gas from the second impeller to theblower outlet in a radial and axial direction, reduce the velocity ofthe flow of gas from the second impeller, and increase the pressure ofthe flow of gas from the second impeller, (r) each of the plurality ofsecond stator vanes may have a constant depth in a radial direction andan increasing width in a circumferential direction from the top ring tothe base ring, and/or (s) each top ring may include a top ring recessand each base ring may include a base ring recess, the top ring recessand the base ring recess may allow a flexible printed circuit boardassembly (PCBA) to pass therethrough.

Another aspect of the present technology is directed to a blower for arespiratory pressure therapy (RPT) system, the blower being configuredto generate a flow of air at a therapeutic pressure of at least 6 cmH2Oabove ambient air pressure. The blower may comprise: a motor having afirst end and a second end; a shaft having a first shaft end extendingfrom the first end of the motor and a second shaft end extending fromthe second end of the motor; an impeller arranged on each of the firstshaft end and the second shaft end such that both impellers are drivensimultaneously by the motor; a stator corresponding to each of the firstend of the motor and the second end of the motor, the stator positioneddownstream of the impeller along the flow of air generated by the blowerin use; a blower outlet positioned downstream of each stator; a housingcorresponding to each of the first end of the motor and the second endof the motor, each housing being shaped and dimensioned to at leastpartially enclose each impeller and each stator and at least partiallydefine a blower inlet, and each housing at least partially defining thecorresponding blower outlet such that the blower outlets are adjacent toone another; and a flow path for the flow of air passing from eachblower inlet, past each impeller, through each stator, and out eachblower outlet.

In examples, (a) each impeller and each second may be at least partiallycontained within the corresponding housing such that the flow of airtravelling along the flow path past the impeller and through the statoralso passes through the housing, (b) each housing may at least partiallydefine the corresponding blower outlet, (c) each housing may comprise amounting structure to connect the blower to the RPT system, (d) eachmounting structure may comprise a pair of mounting rails extendingaround the outer circumference of each housing, (e) each housing may beconstructed to dampen sound and vibration, (f) each housing may comprisea rigid material to provide structural integrity and a less rigid,elastically deformable material overmolded to the rigid material todampen sound and vibration, (g) each impeller may comprise an impellerhub, impeller vanes extending radially from the impeller hub, and animpeller shroud, (h) each of the impeller vanes may comprise a firstimpeller vane portion that extends only in a radial direction and asecond impeller vane portion that extends in a radial and axialdirection, (i) the first impeller vane portion of each of the impellervanes of each first impeller and each second impeller may have aconstant cross-section and may be radially inward relative to the secondimpeller vane portion, (j) the second impeller vane portion may have avariable cross-section and may be radially outward relative to the firstimpeller vane portion, (k) the constant cross-section of the firstimpeller vane portion may be thinner than the variable cross-section ofthe second impeller vane portion, (l) each impeller shroud may comprisea first impeller shroud portion that extends only in a radial directionand a second impeller shroud portion that extends in a radial and axialdirection, (m) the impeller vanes of each impeller may be swept forwardrelative to the direction of rotation during operation, (n) each statormay comprise a top ring, a base ring, and a plurality of stator vanesthat join the top ring and the base ring, (o) the plurality of statorvanes may direct the flow of air from the impeller to the blower outletin a radial and axial direction, reduce the velocity of the flow of airfrom the impeller, and increase the pressure of the flow of air from theimpeller, (p) each of the plurality of stator vanes may have a constantdepth in a radial direction and an increasing width in a circumferentialdirection from the top ring to the base ring, and/or (q) each top ringmay include a top ring recess and each base ring may include a base ringrecess, the top ring recess and the base ring recess allowing a flexibleprinted circuit board assembly (PCBA) to pass therethrough.

Another aspect of the present technology is directed to a vent assemblyfor discharging gas from a plenum chamber to atmosphere. The ventassembly includes: a base; at least one vent hole extension extendingfrom the base and at least partially defining a passage; at least onevent hole passing through the at least one vent hole extension from thepassage to atmosphere; and at least one flexible membrane attached tothe at least one vent hole extension, the at least one flexible membranebeing configured to cover the at least one vent hole in a closedposition to prevent gas from being discharged from the passage toatmosphere, and the at least one flexible membrane being configured notto cover the at least one vent hole in an open position to allow gas tobe discharged to atmosphere from the passage.

In examples, (a) the at least one vent hole extension may include aninterior vent hole surface, each at least one vent hole passing throughthe interior vent hole surface to the passage, (b) the at least oneflexible membrane may be attached to the at least one vent holeextension at the interior vent hole surface, (c) the at least one venthole extension may include an exterior vent hole surface, each at leastone vent hole passing through the exterior vent hole surface toatmosphere, (d) the at least one vent hole extension may comprise aninternal surface, and the vent hole extension may have a generallytriangular cross-section formed by the interior vent hole surface, theexterior vent hole surface, and the internal surface, (e) the interiorvent hole surface may slope downwardly into the interior of the ventassembly relative to a flow of pressurized gas passing through thepassage, (f) the at least one vent hole extension may comprises twodiametrically opposed vent hole extensions, the at least one flexiblemembrane may comprise two flexible membranes, each of the two flexiblemembranes attached to a corresponding one of the two diametricallyopposed vent hole extensions, and the vent assembly may comprise adivider positioned between the two diametrically opposed vent holeextensions to form a first passage and a second passage, (g) the twoflexible membranes may not contact the divider in the open position, (h)the at least one flexible membrane may be constructed of an elasticallydeformable material, and/or (i) the at least one flexible membrane maybe cantilevered to the at least one vent hole extension.

Another aspect of the present technology is directed to a respiratorypressure therapy (RPT) system comprising: at least one housing portionat least partially defining a plenum chamber pressurisable to atherapeutic pressure of at least 6 cmH₂O above ambient air pressure; aseal-forming structure constructed and arranged to form a seal with aregion of the patient's face at or surrounding an entrance to thepatient's airways such that a flow of air at said therapeutic pressureis delivered to at least the entrance to the patient's nares, theseal-forming structure constructed and arranged to maintain saidtherapeutic pressure in the plenum chamber throughout the patient'srespiratory cycle in use; a positioning and stabilising structureconstructed and arranged to provide an elastic force to hold theseal-forming structure in a therapeutically effective position on thepatient's head, the positioning and stabilising structure comprising atie, a lateral portion of the tie being constructed and arranged tooverlie a region of the patient's head superior to the otobasionsuperior in use, and a superior portion of the tie being constructed andarranged to overlie a region of the patient's head in a region of theparietal bone in use, wherein the positioning and stabilising structurehas a non-rigid decoupling portion; a blower configured to generate theflow of air and pressurise the plenum chamber to the therapeuticpressure, the blower having a motor, the blower being connected to theplenum chamber such that in use the blower is suspended from thepatient's head and an axis of rotation of the motor is generallyperpendicular to the patient's sagittal plane; and a power supplyconfigured to provide electrical power to the blower, wherein the atleast one housing portion comprises the vent assembly of described inthe examples of the two preceding paragraphs.

Of course, portions of the aspects may form sub-aspects of the presenttechnology. Also, various ones of the sub-aspects and/or aspects may becombined in various manners and also constitute additional aspects orsub-aspects of the present technology.

Other features of the technology will be apparent from consideration ofthe information contained in the following detailed description,abstract, drawings and claims.

1. BRIEF DESCRIPTION OF THE DRAWINGS

The present technology is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in whichlike reference numerals refer to similar elements including:

4.1 Treatment Systems

FIG. 1 shows a system including a patient 1000 wearing a patientinterface 3000, in the form of nasal pillows, receiving a supply of airat positive pressure from an RPT device 4000. Air from the RPT device4000 is humidified in a humidifier 5000, and passes along an air circuit4170 to the patient 1000. A bed partner 1100 is also shown. The patientis sleeping in a supine sleeping position.

4.2 Respiratory System and Facial Anatomy

FIG. 2 shows an overview of a human respiratory system including thenasal and oral cavities, the larynx, vocal folds, oesophagus, trachea,bronchus, lung, alveolar sacs, heart and diaphragm.

4.3 Patient Interface

FIG. 3 shows a patient interface in the form of a nasal mask inaccordance with one form of the present technology.

4.4 RPT Device

FIG. 4A shows an RPT device in accordance with one form of the presenttechnology.

FIG. 4B is a schematic diagram of the pneumatic path of an RPT device inaccordance with one form of the present technology. The directions ofupstream and downstream are indicated.

FIG. 4C is a schematic diagram of the electrical components of an RPTdevice in accordance with one form of the present technology.

4.5 Breathing Waveforms

FIG. 5 shows a model typical breath waveform of a person while sleeping.

4.6 Respiratory Pressure Therapy (RPT) System

FIG. 6A depicts a side schematic view of a patient wearing an RPT systemaccording to an example of the present technology.

FIG. 6B depicts a perspective view of the pressure generating featuresof an RPT system according to an example of the present technology.

FIG. 6C depicts a cross-sectional view of the pressure generatingfeatures of an RPT system according to an example of the presenttechnology.

FIG. 7A depicts a perspective view of a blower of an RPT systemaccording to an example of the present technology.

FIG. 7B depicts a perspective view of a partially disassembled blower ofan RPT system according to an example of the present technology.

FIG. 7C depicts another perspective view of a partially disassembledblower of an RPT system according to an example of the presenttechnology.

FIG. 7D depicts another perspective view of a partially disassembledblower of an RPT system according to an example of the presenttechnology.

FIG. 7E depicts a cross-sectional view of a blower of an RPT systemaccording to an example of the present technology.

FIG. 7F depicts an exploded view of a blower of an RPT system accordingto an example of the present technology.

FIG. 8A depicts a perspective view of an impeller of a blower of an RPTsystem according to an example of the present technology.

FIG. 8B depicts another perspective view of an impeller of a blower ofan RPT system according to an example of the present technology.

FIG. 8C depicts another perspective view of an impeller of a blower ofan RPT system according to an example of the present technology.

FIG. 8D depicts a side elevation view of an impeller of a blower of anRPT system according to an example of the present technology.

FIG. 8E depicts a cross-sectional view of an impeller of a blower of anRPT system taken through line 8E of FIG. 8D according to an example ofthe present technology.

FIG. 8F depicts a cross-sectional view of an impeller of a blower of anRPT system taken through line 8F of FIG. 8D according to an example ofthe present technology.

FIG. 8G depicts a cross-sectional view of an impeller of a blower of anRPT system taken through line 8G of FIG. 8D according to an example ofthe present technology.

FIG. 8H depicts a cross-sectional view of an impeller of a blower of anRPT system taken through line 8H of FIG. 8D according to an example ofthe present technology.

FIG. 8I depicts a cross-sectional view of an impeller of a blower of anRPT system taken through line 8I of FIG. 8D according to an example ofthe present technology.

FIG. 8J depicts a cross-sectional view of an impeller of a blower of anRPT system taken through line 8J of FIG. 8D according to an example ofthe present technology.

FIG. 8K depicts a plan view of an impeller of a blower of an RPT systemaccording to an example of the present technology.

FIG. 8L depicts a cross-sectional view of an impeller of a blower of anRPT system taken through line 8L of FIG. 8K according to an example ofthe present technology.

FIG. 8M depicts a cross-sectional view of an impeller of a blower of anRPT system taken through line 8M of FIG. 8K according to an example ofthe present technology.

FIG. 9A depicts a perspective view of a first stator of a blower of anRPT system according to an example of the present technology.

FIG. 9B depicts a side elevation view of a first stator of a blower ofan RPT system according to an example of the present technology.

FIG. 9C depicts a plan view of a first stator of a blower of an RPTsystem according to an example of the present technology.

FIG. 9D depicts a plan view of a first stator of a blower of an RPTsystem with the stator upper shroud shown in phantom according to anexample of the present technology.

FIG. 9E depicts a cross-sectional view of a first stator of a blower ofan RPT system taken through line 9E-9E of FIG. 9D according to anexample of the present technology.

FIG. 9F depicts a cross-sectional view of a first stator of a blower ofan RPT system taken through line 9F-9F of FIG. 9D according to anexample of the present technology.

FIG. 10A depicts another cross-sectional view of a partiallydisassembled blower of an RPT system according to an example of thepresent technology.

FIG. 10B depicts a perspective view of an end of a partiallydisassembled blower of an RPT system according to an example of thepresent technology.

FIG. 10C depicts a cross-sectional view of an end of a partiallydisassembled blower of an RPT system taken through line 10C-10C of FIG.10A according to an example of the present technology.

FIG. 10D depicts a side elevation view of a first stator of a blower ofan RPT system according to an example of the present technology.

FIG. 10E depicts a cross-sectional view of a first stator of a blower ofan RPT system taken through line 10E-10E of FIG. 10D according to anexample of the present technology.

FIG. 11A depicts a perspective view of a second stator of a blower of anRPT system according to an example of the present technology.

FIG. 11B depicts another perspective view of a second stator of a blowerof an RPT system according to an example of the present technology.

FIG. 11C depicts another perspective view of a second stator of a blowerof an RPT system according to an example of the present technology.

FIG. 12A depicts a plan view of an impeller of a blower of an RPT systemaccording to an example of the present technology.

FIG. 12B depicts a perspective view of an impeller of a blower of an RPTsystem according to an example of the present technology.

FIG. 13A depicts a plan view of an impeller of a blower of an RPT systemaccording to an example of the present technology.

FIG. 13B depicts a perspective view of an impeller of a blower of an RPTsystem according to an example of the present technology.

FIG. 14 depicts an exploded view of a blower of an RPT system accordingto an example of the present technology.

FIG. 15A depicts an anterior perspective view of a patient wearing anRPT system according to an example of the present technology.

FIG. 15B depicts another anterior perspective view of a patient wearingan RPT system according to an example of the present technology.

FIG. 15C depicts a posterior perspective view of a patient wearing anRPT system according to an example of the present technology.

FIG. 16A depicts an anterior perspective view of a patient wearing anRPT system according to an example of the present technology.

FIG. 16B depicts another perspective view of a patient wearing an RPTsystem according to an example of the present technology.

FIG. 17 depicts a perspective view of an RPT system according to anexample of the present technology.

FIG. 18A depicts a side view of a vent assembly according to an exampleof the present technology.

FIG. 18B depicts a top perspective view of a vent assembly according toan example of the present technology.

FIG. 18C depicts a cross-sectional perspective view of a vent assemblyaccording to an example of the present technology.

FIG. 18D depicts a bottom perspective view of a vent assembly accordingto an example of the present technology.

FIG. 18E depicts a top view of a vent assembly according to an exampleof the present technology.

FIG. 18F depicts a side cross-sectional view of a vent assembly in anneutral state according to an example of the present technology.

FIG. 18G depicts a side cross-sectional view of a vent assembly duringventing according to an example of the present technology.

FIG. 18H depicts a side cross-sectional view of a vent assembly while aflow of pressurized gas is passing through the vent assembly to apatient according to an example of the present technology.

FIG. 19A shows an impeller in accordance with one form of the presenttechnology.

FIG. 19B shows a cross-section of the impeller shown in FIG. 19A.

FIG. 19C shows an isometric view of the impeller shown in FIG. 19A.

FIG. 19D shows an elevation view of the impeller shown in FIG. 19A.

FIG. 19E shows an elevation view of the impeller shown in FIG. 19A,indicating cross sections taken for FIGS. 19F-19N.

FIGS. 19F-19N show plan views of an impeller in accordance with one formof the present technology at various cross sections as indicated on FIG.19E.

FIG. 19O shows an elevation view of an impeller in accordance with oneform of the present technology.

FIG. 19P shows an isometric view of the impeller shown in FIG. 19O.

FIG. 19Q shows a plan view of the impeller shown in FIG. 19O, indicatingcross-sections taken for FIGS. 19R-19S.

FIGS. 19R-19S show cross-sections of the impeller as indicated on FIG.19Q.

FIG. 19T shows an isometric view of an impeller in accordance with oneform of the present technology.

FIG. 19U shows an exploded view of the impeller shown in FIG. 19T.

FIG. 19V shows a bottom isometric view of the impeller shown in FIG.19T.

FIG. 19W shows an exploded view of the impeller shown in FIG. 19V.

FIG. 19X shows a cross-section of the impeller as indicated on FIG. 19T.

FIG. 19Y shows an isometric view of an impeller in accordance with oneform of the present technology.

FIG. 19Z shows a bottom isometric view of the impeller shown in FIG.19Y.

FIG. 19AA shows a plan view of the impeller shown in FIG. 19Y,indicating cross-sections taken for FIGS. 19DD-19EE.

FIG. 19BB shows an exploded view of the impeller shown in FIG. 19Y.

FIG. 19CC shows another exploded view of the impeller shown in FIG. 19Y.

FIGS. 19DD-19EE show cross-sections of the impeller as indicated on FIG.19AA.

FIG. 19FF shows a cross-section of a blower for an RPT device includingimpellers in accordance with one form of the present technology.

FIG. 19GG is an enlarged portion of the blower as indicated on FIG.19FF.

5. DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY

Before the present technology is described in further detail, it is tobe understood that the technology is not limited to the particularexamples described herein, which may vary. It is also to be understoodthat the terminology used in this disclosure is for the purpose ofdescribing only the particular examples discussed herein, and is notintended to be limiting.

The following description is provided in relation to various exampleswhich may share one or more common characteristics and/or features. Itis to be understood that one or more features of any one example may becombinable with one or more features of another example or otherexamples. In addition, any single feature or combination of features inany of the examples may constitute a further example.

5.1 Therapy

In one form, the present technology comprises a method for treating arespiratory disorder comprising the step of applying positive pressureto the entrance of the airways of a patient 1000.

In certain examples of the present technology, a supply of air atpositive pressure is provided to the nasal passages of the patient viaone or both nares.

In certain examples of the present technology, mouth breathing islimited, restricted or prevented.

5.2 Treatment Systems

In one form, the present technology comprises an apparatus or device fortreating a respiratory disorder. The apparatus or device may comprise anRPT device 4000 for supplying pressurised air to the patient 1000 via anair circuit 4170 to a patient interface 3000.

FIG. 6A depicts a schematic of a respiratory pressure therapy (RPT)system worn by a patient according to an example of the presenttechnology. The RPT system includes a blower 4142 (FIG. 6B) to provide aflow of gas to the patient at a pressure greater than ambient, aseal-forming structure 3100 to form a seal with the entrance to thepatient's airways, a plenum chamber 3200 (FIG. 6B) which supports theblower 4142 and is pressurized by the blower 4142 during therapy, alateral portion of a tie of a positioning and stabilising structure3303, a superior portion of a tie of a positioning and stabilisingstructure 3304, and a posterior portion of a tie of a positioning andstabilising structure 3305 to secure the RPT system to the patientduring therapy, and a power supply 4210 to drive the blower and anyother electrical components. Details of the various components of theexemplary RPT system are provided in the corresponding subsectionsbelow.

According the example of the present technology that is depicted in FIG.6A, the RPT system may be completely self-contained and patient-worn. Inother words, all of the components need for RPT therapy are combinedinto one system that may be worn and supported entirely by the patient'shead during use. Conventionally, RPT systems include a patient interface3000 that is worn by the patient and includes a plenum chamber 3200 thatis pressurized to the therapy pressure with a flow of gas, aseal-forming structure 3100 that forms a seal with the entrance to thepatient's airways to provide a substantially sealed path for the flow ofgas, and a positioning and stabilising structure 3300 that secures theseal-forming structure 3100 and plenum chamber 3200 during use. In suchconventional systems, these are the only components that are actuallysupported on the patient's head. An example of these conventionalsystems are depicted in FIG. 1.

A respiratory pressure therapy (RPT) device 4000 is also provided inconventional systems to generate the flow of gas at a pressure greaterthan ambient. Due to the pressure and flow rate necessary for adequatetherapy, the RPT device 4000 is typically a relatively large device thathas been typically provided as a separate device that is supported near,but not on, the patient during therapy. In other words, prior art RPTdevices 4000 are relatively large in size and weight due totechnological limitations such that an adequate therapy pressure andflow rate can only be generated by such a large device that the patientcannot comfortably wear the RPT device during use. Accordingly, the RPTdevice 4000 is typically located on the patient's nightstand or similarstructure to keep the RPT device 4000 in close proximity. Since thepatient will typically be in his or her bed wearing the patientinterface 3000 and the RPT device 4000 is located nearby, an air circuit4170 is also included to provide the flow of pressurised gas from theRPT device 4000 to the patient interface 3000. Furthermore, since theconventional RPT device 4000 is located at a distance from the patientsuch that the air circuit 4170 is required to deliver the flow of gas tothe patient, the RPT device 4000 must be powerful enough to account forpressure losses associated with directing the flow of gas down the aircircuit 4170 to the patient interface 3000.

While the overall arrangement described above has been the norm inrespiratory therapy for several decades, the present technologyrepresents an improvement by allowing the entire RPT system to becomfortably worn by the patient during therapy. The features describedin detail below explain how the various components can be reduced insize and weight sufficiently for the patient to wear comfortably and, incases where the RPT system is used to treat sleep-disordered breathing,sleep with the entire system on the head.

An example of the present technology depicted in FIG. 6A is arespiratory pressure therapy (RPT) system that includes a plenum chamber3200 pressurisable to a therapeutic pressure of at least 6 cmH₂O aboveambient air pressure. The RPT system also includes a seal-formingstructure 3100 constructed and arranged to form a seal with a region ofthe patient's face at or surrounding an entrance to the patient'sairways such that a flow of gas at said therapeutic pressure isdelivered to at least the entrance to the patient's nares. Theseal-forming structure 3100 may be constructed and arranged to maintainsaid therapeutic pressure in the plenum chamber 3200 throughout thepatient's respiratory cycle in use. A positioning and stabilisingstructure 3300 constructed and arranged to hold the seal-formingstructure in a therapeutically effective position on the patient's headmay also be provided. The positioning and stabilising structure 3300 mayinclude at least one tie. A lateral portion of the tie 3303 may beconstructed and arranged to overlie a region of the patient's headsuperior to the otobasion superior in use. A superior portion 3304 ofthe tie may be constructed and arranged to overlie a region of thepatient's head in a region of the parietal bone in use. A posteriorportion 3305 of the tie may be constructed and arranged to overlie aregion of the patient's head in a region of the occipital bone in use.The positioning and stabilising structure 3300 may include a non-rigiddecoupling portion. The RPT system may also include a blower 4142 thatis configured to generate the flow of gas and pressurise the plenumchamber 3200 to the therapeutic pressure. The blower 4142 may beconnected to the plenum chamber 3200 such that the blower 4142 issupported from the patient's head in use. The blower 4142 may bearranged with respect to the patient's head in use such that the axis ofrotation of the motor 4145 is perpendicular to the patient's sagittalplane. A power supply 4210 to provide electrical power to the blower4142 may also be included in the RPT system. The plenum chamber 3200,seal-forming structure 3100, and the blower 4142 may be arranged so asnot to extend beyond the patient's mental protuberance in use.

FIGS. 15A-15C and 16A-16C depict other examples of the RPT system of thepresent technology. FIG. 17 depicts the RPT system in isolation, i.e.,not worn by a patient, and without the positioning and stabilizingstructure 3300. These examples include the primary components describedabove and in greater detail below, including, inter alia, theseal-forming structure 3100, the plenum chamber, the positioning andstabilising structure 3300, the blower 4142 (not visible in theseviews), the vent assembly 3400, the power supply 4210, and the centralcontroller 4230. These examples will be described in greater detailbelow.

5.3 Patient Interface

A non-invasive patient interface 3000 in accordance with one aspect ofthe present technology comprises the following functional aspects: aseal-forming structure 3100, a plenum chamber 3200, a positioning andstabilising structure 3300, a vent or vent assembly 3400, and a foreheadsupport 3700. In some forms a functional aspect may be provided by oneor more physical components. In some forms, one physical component mayprovide one or more functional aspects. In use the seal-formingstructure 3100 is arranged to surround an entrance to the airways of thepatient so as to facilitate the supply of air at positive pressure tothe airways.

If a patient interface is unable to comfortably deliver a minimum levelof positive pressure to the airways, the patient interface may beunsuitable for respiratory pressure therapy.

The patient interface 3000 in accordance with some forms of the presenttechnology may be constructed and arranged to be able to provide asupply of air at a positive pressure of at least 6, 10 or 20 cmH₂O withrespect to ambient.

As described in the preceding subsection, the RPT system of the presenttechnology may be understood to comprise a number of the basic elementsof a conventional patient interface 3000 that are described below ingreater detail, e.g., a seal-forming structure 3100, a plenum chamber3200, and a positioning and stabilising structure 3300. The exemplaryRPT system of the present technology improves upon the conventionalpatient interface 3000 by adding the blower 4142 directly to the patientinterface 3000, e.g., on the plenum chamber 3200, to provide thepressurised flow of gas. Thus, the blower 4142 may be understood to besuspended or supported on the patient's head by the patient interface.The power supply 4210 may also be provided directly to the patientinterface 3000, e.g., on the positioning and stabilising structure 3300,to provide electrical power to the blower 4142 and any other componentsas needed. By arranging the blower 4142 and the power supply 4210 on thepatient interface 3000, the need for the air circuit 4170 and any otherwires or connections extending from the patient is eliminated.Accordingly, undesirable effects and forces on the patient interface3000, such as tube drag caused by the air circuit 4170 may be reduced oreliminated.

5.3.1 Seal-Forming Structure

In one form of the present technology, a seal-forming structure 3100provides a target seal-forming region, and may additionally provide acushioning function. The target seal-forming region is a region on theseal-forming structure 3100 where sealing may occur. The region wheresealing actually occurs—the actual sealing surface—may change within agiven treatment session, from day to day, and from patient to patient,depending on a range of factors including for example, where the patientinterface was placed on the face, tension in the positioning andstabilising structure and the shape of a patient's face.

In certain forms of the present technology, the seal-forming structure3100 is constructed from a biocompatible material, e.g., siliconerubber.

A seal-forming structure 3100 in accordance with the present technologymay be constructed from a soft, flexible, resilient material such assilicone.

In another form of the present technology, the RPT system is supportedon the patient's head solely by the sealing engagement of theseal-forming structure 3100 with the entrance(s) to the patient'sairways. For example, the seal-forming structure 3100 may compriseprongs or nasal inserts that are inserted into the patient's nares andthe prongs or nasal inserts are shaped and dimensioned to provide asufficiently rigid connection to allow the RPT system to be supportedonly by that connection. Thus, the positioning and stabilising structure3300 features described below may be eliminated completely from the RPTsystem or the positioning and stabilising structure 3300 may at least befurther simplified.

The seal-forming structure 3100 of the present technology may comprise asilicone cushion that encloses the blower 4142 and is connected to theplenum chamber 3200 such that the blower 4142 is supported by thepositioning and stabilising structure 3300 and the seal-formingstructure 3100 in use. In other words, the seal-forming structure 3100may be configured to suspend the RPT system by providing a location forsupport and engagement with the patient's face. Accordingly, theseal-forming structure 3100 may also isolate vibration generated by theblower 4142 from the patient's face.

The seal-forming structure 3100 of the present technology may beconstructed such that no part thereof enters the patient's mouth in use.Also, the seal-forming structure 3100 of the present technology may beconstructed such that it does not extend internally of the patient'sairways. As described above, the seal-forming structure 3100 of thepresent technology may comprise a pair of nasal puffs, or nasal pillows,each nasal puff or nasal pillow being constructed and arranged to form aseal with a respective naris of the nose of the patient. Theseal-forming structure 3100 of the present technology may form a seal inuse on a nose bridge region or on a nose-ridge region of the patient'sface and may form a seal in use on an upper lip region of the patient'sface. The seal-forming structure 3100 of the present technology may forma seal in use on a nose bridge region or on a nose-ridge region of thepatient's face and may form a seal in use on a chin-region of thepatient's face.

The seal-forming structure 3100 of the present technology may comprisean elastically deformable material that is less rigid than the plenumchamber 3200. For example, the elastically deformable material may besilicone rubber, e.g., liquid silicone rubber (LSR) or compressionmolded silicone rubber (CMSR). A portion of the seal-forming structure3100 may substantially enclose the plenum chamber 3200 and the blower4142 while allowing at least an inlet 4143 of the blower 4142 to remainexposed. The seal-forming structure 3100 may be shaped and dimensionedto at least partially isolate the patient's head from vibration anddampen sound generated by the blower 4142 in use. The elasticallydeformable material of the seal-forming structure 3100 may be selectedto at least partially isolate the patient's head from vibration anddampen sound generated by the blower 4142 in use.

Elastic deformability of the seal-forming structure 3100 may help theRPT system absorb motion of the heavier components (e.g., the blower4142) to allow the RPT system to remain in place during use. Otherwise,if the seal-forming structure 3100 provided too stiff of an interfacewith the patient's head, the patient's movements might disrupt theconnection. Furthermore, constructing the seal-forming structure 3100from a material with vibration isolation and/or dampening properties maybe advantageous where the motor 4145 of the blower 4142 is capable ofhigh rotational speeds (e.g., 50,000 rpm to 80,000 rpm) and/or where thecontrol system may change the rotational speed frequently during therapysuch that the torque associated with speed changes causes the RPT systemto move relative to the patient's head. Accordingly, the vibrationdampening properties of the material may help to isolate the patient'shead from what would otherwise be disruptive forces transferred to thepatient's head. In addition, a reduced inertia of the blower, such asfrom a reduced diameter of an impeller, may further improve aperformance of the seal-forming structure 3100.

Alternatively, the RPT system may comprise a cover constructed of anelastically deformable material that is less rigid than the plenumchamber 3200. The cover may substantially enclose the plenum chamber3200 and the blower 4142 while allowing at least an inlet 4143 of theblower 4142 to remain exposed. The cover may be shaped and dimensionedto at least partially isolate the patient's head from vibration anddampen sound generated by the blower 4142 in use. The elasticallydeformable material of the cover may be selected to at least partiallyisolate the patient's head from vibration and dampen sound generated bythe blower 4142 in use. In this alternative, a seal-forming structure3100 may be included with the features described above, but may be aseparate component from the cover. Such a construction may beadvantageous so that the materials, shape, and dimensions of theseal-forming structure 3100 can be optimized for its intended functions,while allowing the materials, shape, and dimensions of the cover to beoptimized for its intended functions.

The examples shown in FIGS. 15A-15C, 16A-16C, and 17 include aseal-forming structure 3100. The seal-forming structure 3100 in theseexamples is in the form of nasal pillows, each forming an individualseal with the corresponding nostril. However, other variations areenvisioned, such as a nasal cushion that provides the flow ofpressurized gas to the patient's nostrils but not the mouth, a nasalcradle cushion that provides the flow of pressurized gas to thepatient's nostrils but not the mouth and that seals at the base of thepatient's nose and does not extend above the bridge or the tip of thepatient's nose, a full-face cushion with a single opening that providesthe flow of pressurized gas to the patient's nostrils and mouth, or anoro-nasal cushion that includes separate openings to provide the flow ofpressurized gas to the patient's nose and mouth separately.

In the examples shown in FIGS. 15A-15C, 16A-16C, and 17, theseal-forming structure 3100 is connected to the plenum chamber 3200 atthe upper housing portion 4132. The connection may be permanent (i.e.,the seal-forming structure 3100 cannot be separated from the upperhousing portion 4132 without damaging one or both components) or theseal-forming structure 3100 may be removable to allow for cleaning orreplacement. The seal-forming structure 3100 may be made from a flexiblematerial such as liquid silicone rubber, and may be overmolded to theupper housing portion 4132 in the permanent connection variation.Alternatively, the permanent connection may be formed by molding theseal-forming structure 3100 onto the upper housing portion 4132 suchthat a mechanical interlock is formed. In the removable connectionexamples, the upper housing portion 4132 and the seal-forming structure3100 may include structures shaped to form a mechanical interlock thatis separable by deforming one or both of the upper housing portion 4132and the seal-forming structure 3100.

5.3.2 Plenum Chamber

The plenum chamber 3200 of the exemplary RPT system may be formed by atleast one housing portion. In the example depicted in FIGS. 6A-6C, anupper housing portion 4132 and a lower housing portion 4133 form theplenum chamber 3200. Also in this example, the blower 4142 may becontained at least partially within the plenum chamber 3200 such thatwhen the blower 4142 is operated the plenum chamber 3200 is pressurizedby the flow of gas generated by the blower 4142. The upper housingportion 4132 may also have a plenum chamber outlet 4131. The flow of gasgenerated by blower 4142 may pass through the plenum chamber 3200 to atleast the entrance to the patient's nares in use via the plenum chamberoutlet 4131. Actual contact with the face is provided by theseal-forming structure 3100. The seal-forming structure 3100 may bejoined to and extend in use about the entire perimeter of at least theplenum chamber outlet 4131. In some forms, the plenum chamber 3200 andthe seal-forming structure 3100 are formed from a single homogeneouspiece of material.

The upper housing portion 4132 and the lower housing portion 4133 may beat least partially separable to allow the blower 4142 to be removed fromthe plenum chamber 3200. For example, the housing portion(s) may bejoined at one side in a clamshell arrangement to allow the plenumchamber 3200 to be opened and closed so that the blower 4142 can beremoved. Thus, beneficially, a user may be able to choose from aplurality of patient interfaces to use with the blower 4142 according tothe user's preference.

According to some form of the present technology, a kit may comprise ablower 4142 and one of: a plurality of plenum chambers 3200 configuredto receive the blower 4142, and/or a plurality of positioning andstabilising structures 3300. The kit may comprise further componentssuch as a power supply, to allow a user to configure and/or assemble anRPT system for use according to their preferences from such a kit.

The housing portion(s) of the plenum chamber 3200 may also comprise atleast one sealing structure to seal between the upper housing portion4132 and the lower housing portion 4133 and/or along the line ofseparation in the clamshell arrangement described above.

In another example of the present technology, the entire plenum chamber3200, e.g., between the upper housing portion 4132 and the lower housingportion 4133, may be comprised of an elastically deformable material,such as silicone. The plenum chamber 3200 according to this example maycomprise two separate pieces, i.e., the upper housing portion 4132 andthe lower housing portion 4133, that are joined together to form theplenum chamber 3200 or the plenum chamber 3200 may comprise a singlestructure, e.g., in which the upper housing portion 4132 and the lowerhousing portion 4133 are formed from a single, homogeneous piece ofmaterial.

In certain forms of the present technology, the plenum chamber 3200 isat least partly constructed from a transparent material, e.g., atransparent polycarbonate. The use of a transparent material can reducethe obtrusiveness of the patient interface, and help improve compliancewith therapy. The use of a transparent material can aid a clinician toobserve how the patient interface is located and functioning.

In certain forms of the present technology, the plenum chamber 3200 isat least partly constructed from a translucent material. The use of atranslucent material can reduce the obtrusiveness of the patientinterface, and help improve compliance with therapy.

In one form, the plenum chamber 3200 may comprise a lower housingportion 4133 constructed from a soft, damped material such as silicone,and an upper housing portion 4132 constructed from a rigid material suchas a polycarbonate. Alternatively, FIGS. 6D and 6E depict a variationthat excludes the upper housing portion 4132 such that the seal-formingstructure 3100 would be directly connected to the lower housing portion4133, which would reduce dead space within the plenum chamber 3200.

Additionally, FIG. 6E shows a heat and moisture exchanger (HME) 6000positioned within the lower housing portion 4133 and supported by theHME retention structure 4135.

The plenum chamber 3200 may also include at least one attachmentstructure 4130 to attach the positioning and stabilising structure 3300to secure the RPT system to the patient's head in use. The exampledepicted in FIGS. 6A-6C shows the attachment structure 4130 formedintegrally with the lower housing portion 4133 as one homogeneous pieceof material. The attachment structure 4130 may also be a separatecomponent that is attached to one of the housing portions of the plenumchamber 3200. The attachment structure 4130 may be joined to thepositioning and stabilising structure 3300 by clips or by looping strapsof the positioning and stabilising structure through correspondingattachment structures 4130.

The RPT system of the present technology may also comprise a heat andmoisture exchanger (HME) that absorbs heat and moisture from gas exhaledby the patient. The heat and moisture absorbed by the HME during therapymay then be transferred to the flow of gas generated by the blower 4142to humidify the flow of gas before it reaches the patient's airways.Providing the RPT system with an HME may obviate the need forconventional powered humidification. According to the example depictedin FIGS. 6A-6C, the HME may be located within the plenum chamber 3200such that it that is positioned in the flow of gas and downstream of theblower 4142. As can be seen in FIG. 6B, an HME retention structure 4135is provided on the lower housing portion 4133 to retain the HME withinthe plenum chamber 3200, but the HME retention structure 4135 may beprovided on the upper housing portion 4132 instead, may be a part of theHME or may be a separable part altogether. As will be described below,the HME may be provided within the plenum chamber 3200 and downstream ofthe blower 4142 because the RPT system may be unvented such that thepatient's exhalate travels along the same path but in an oppositedirection to the flow of gas generated by the blower 4142 for therapy.Therefore, the inhaled and exhaled flows of gas will both pass throughthe HME.

The HME of the present technology may be made of a foam material or apaper material. Other porous materials are also envisioned. Accordingly,the HME may also act as a filter.

The examples shown in FIGS. 15A-15C, 16A-16C, and 17 include a plenumchamber 3200 that may be formed by the upper housing portion 4132 andthe lower housing portion 4133. In the examples shown in FIGS. 6A-6C,the upper housing portion 4132 and the lower housing portion 4133 areseparate components that may be joined together to form the plenumchamber 3200 and to allow access to components therein. However, in theexamples shown in FIGS. 15A-15C, 16A-16C, and 17, the upper housingportion 4132 and the lower housing portion 4133 are a single, unitarycomponent that forms the plenum chamber 3200.

In the examples shown in FIGS. 16A-16C and 17, the upper housing portion4132 includes a vent assembly 3400 that is described in greater detailbelow. The vent assembly 3400 permits gas to be discharged to atmosphereto expel CO₂ exhaled by the patient, which prevents undesirable CO₂rebreathing. The examples shown in FIGS. 15A-15C do not include a ventassembly 3400.

5.3.3 Positioning and Stabilising Structure

The seal-forming structure 3100 of the patient interface 3000 of thepresent technology may be held in sealing position in use by thepositioning and stabilising structure 3300, such as when the RPT deviceis in operation, and/or not in operation.

In one form of the present technology, a positioning and stabilisingstructure 3300 is provided that is configured in a manner consistentwith being worn by a patient while sleeping.

In one form of the present technology, a positioning and stabilisingstructure 3300 is provided with a decoupling portion located between ananterior portion of the positioning and stabilising structure 3300 and aposterior portion of the positioning and stabilising structure 3300. Thedecoupling portion does not resist compression and may be, e.g., aflexible or floppy strap. The decoupling portion is constructed andarranged so that when the patient lies with their head on a pillow, thepresence of the decoupling portion prevents a force on the posteriorportion from being transmitted along the positioning and stabilisingstructure 3300 and disrupting the seal.

In one form of the present technology, a positioning and stabilisingstructure 3300 comprises a strap constructed from a laminate of a fabricpatient-contacting layer, a foam inner layer and a fabric outer layer.

In certain forms of the present technology, a positioning andstabilising structure 3300 comprises a strap that is extensible, e.g.,resiliently extensible.

In some forms, the positioning and stabilising structure 3300 may beconfigured to allow, or support, transmission of at least one of powerand/or signals. For example, the positioning and stabilising structure3300 may comprise, or support thereon, an electrically conductiveportion configured to provide electrical communication therethrough.

In the example of the RPT system depicted in FIG. 6A, the positioningand stabilising structure 3300 may comprise at least one wire 3301supported by the positioning and stabilising structure 3300. The wire(s)3301 may provide electrical communication between the blower 4142 andthe power supply 4210, e.g., a battery, such as for power and/orsignalling. The wire(s) 3301 may be contained within a lateral portion3303 of the positioning and stabilising structure 3300, e.g., one ormore of the ties that pass superior or inferior to the patient'sotobasion superior. The wire 3301 may comprise a relatively thincross-section so as to maintain a low-profile and not be uncomfortablefor the patient. The wire 3301 may be configured such that its rigidityis relatively small in comparison to that of the supporting positioningand stabilising structure 3300, so as to not significantly prevent thepositioning and stabilising structure from conforming to the patient'sface. In one example, the wire 3301 may be in the form of a flexibleprinted circuit (FPC). Such a configuration may beneficially allow apatient to sleep comfortably at night while using the RPT system toreceive respiratory treatment.

For example, the wire 3301 may have a thickness of less than 3 mm. Thewire 3301 may be as thin as 0.5 mm, 0.2 mm or 0.1 mm, allowing thelateral portion 3303 to be flexible and/or thin, such that it mayconform readily to the contours of the patient's face or head withoutbeing uncomfortable. The wire 3301 may be covered in the lateral portion3303, such as by being encapsulated or covered, for example in silicone,foam or in a fabric material. The power supply 4210 may be provided tothe superior portion 3304 of the positioning and stabilising structure3300 such that the wire(s) 3301 pass from the power supply 4210 to theblower 4142 thought the lateral portion of the tie 3303. Of course, thewire 3301 may comprise one or more layers (e.g. for insulation and/orfurther shielding) in addition to its conductive portions, such aspolyester layers in FPC.

The positioning and stabilising structure 3300 may also include at leastone tube 3302 in fluid communication with the plenum chamber 3200 at afirst end via the port 4134 and a pressure transducer at a second end.The tube(s) 3302 may be contained within the lateral portion 3303 of thepositioning and stabilising structure 3300, e.g., one or more of theties that pass superior or inferior to the patient's otobasion superior.

The positioning and stabilising structure 3300 may also include arigidiser arm to increase the rigidity of the lateral ties that join tothe plenum chamber 3200 at the attachment structures 4130. Since theentire RPT system may be supported on the patient's head, the relativelysoft and flexible materials of the positioning and stabilising structure3300 alone may be insufficiently rigid to support the RPT system in use,in particular the blower 4142, the plenum chamber 3200, and theseal-forming structure 3100. By adding rigidiser arms to the lateralties of the positioning and stabilising structure 3300, the weight ofthe RPT system can be more adequately supported in the desired positionand only exceptional outside forces would be able to disrupt the sealingengagement with the patient's airways. The rigidiser may also at leastpartly cover a wire 3301 such as on one side of the wire 3301 or enclosethe wire.

Furthermore, the length of at least one of the ties of the positioningand stabilising structure 3300 may be adjustable to allow the patient toset the tension generated by the positioning and stabilising structure3300. Thus, the patient can ensure that the RPT system, in particularthe positioning and stabilising structure 3300, fits comfortably whilemaintaining an adequate seal and a desired position.

The examples shown in FIGS. 15A-15C and 16A-16C include a positioningand stabilising structure 3300. The positioning and stabilisingstructure 3300 of these examples may include lateral portions 3303 thatpass along respective sides of the patient's head. The lateral portions3303 may pass above the patient's ears. The lateral portions 3303 maypass below the patient's eyes. The positioning and stabilising structure3300 of these examples may include a posterior portion 3305 that may beadjustable. For example, the posterior portion 3305 may include a tab3306 that forms a hook-and-loop connection to secure the posteriorportion 3305 at the desired length. The posterior portion 3305 may beinclude one of hook or loop material and the tab 3306 may include theother of hook and loop material. An adjustment mechanism 3308 may alsobe provided to allow adjustment of the superior portion 3304 toaccommodate patient heads of different sizes and shapes.

The positioning and stabilising structure 3300 in the examples shown inFIGS. 15A-15C and 16A-16C may also include one or more wires 3301 thatmay provide power from a power supply 4210 to the blower 4142. Also, thewire(s) 3301 may provide control signals to the blower 4142 from thecentral controller 4230. Additionally, if one or more sensors areincluded, e.g., a pressure sensor within the plenum chamber 3200, theone or more sensors may communicate signals to the central controller4230 via the wire(s) 3301. The wire(s) 3301 may be secured to lateralportions 3303 and/or superior portions 3304 by one or more retainers3307. Additionally, the central controller 4230 may be secured to thepositioning and stabilising structure 3300 with one or more retainers4231, e.g., at the lateral portion 3303 or the superior portion 3304.Also, the power supply 4210 may be secured to the positioning andstabilising structure 3300 with one or more retainers (not shown), e.g.,at the lateral portion 3303 or the superior portion 3304. The powersupply 4210 and/or the central controller 4230 may be contained with ahousing that is connected to the positioning and stabilising structure3300, such as via retainers, adhesives or other methods, such asovermoulding.

5.3.4 Vent

In one form, the patient interface 3000 includes a vent or vent assembly3400 constructed and arranged to allow for the washout of exhaled gases,e.g., carbon dioxide.

In certain forms, the vent or vent assembly 3400 is configured to allowa continuous vent flow from an interior of the plenum chamber 3200 toambient whilst the pressure within the plenum chamber is positive withrespect to ambient. The vent or vent assembly 3400 is configured suchthat the vent flow rate has a magnitude sufficient to reduce rebreathingof exhaled CO2 by the patient while maintaining the therapeutic pressurein the plenum chamber in use.

One form of vent or vent assembly 3400 in accordance with the presenttechnology comprises a plurality of holes, for example, about 20 toabout 80 holes, or about 40 to about 60 holes, or about 45 to about 55holes.

The vent or vent assembly 3400 may be located in the plenum chamber3200. Alternatively, the vent or vent assembly 3400 is located in adecoupling structure, e.g., a swivel.

The exemplary RPT system depicted in FIGS. 6A-6C, may not include avent, e.g., the plenum chamber 3200 may be unvented. Thus, in use thepatient may exhale only through the blower 4142 in opposition to thedirection of the flow of gas generated by the blower 4142 for therapy,e.g., while the blower 4142 continues to operate, and the patient'sexhalate exits the RPT system through the blower inlet 4143.Accordingly, exhalation flow would travel through the blower 4142 tovent to the atmosphere. Moreover, the entire flow of gas travelingthrough the blower 4142 may reverse direction during the patient'sexhalation phase, because the flow of the patient's exhalation exceedsthe flow generated by the blower 4142. To facilitate venting exhalatethrough the blower 4142 and the blower inlet 4143, the blower 4142 maybe arranged near the plenum chamber outlet 4131 and the seal-formingstructure 3100 so that the blower 4142 is, therefore, near the patient.In such an arrangement, the blower 4142 should be sufficiently close toallow enough the exhalate to exit the RPT system prior to the patientbeginning to inhale. Furthermore, the RPT system may be configured toallow breathing out through the blower inlet 4143 with minimal pneumaticresistance.

By arranging the blower 4142 near the patient and allowing venting ofexhalate only through the blower 4142 and the blower inlet 4143, theoverall flow rate required to be generated by the blower 4142 is reducedbecause it is not necessary to account for the vent flow. In otherwords, no vent leak is present during the patient's inhalation thatneeds to be driven by the flow of gas generated by the blower 4142. Thisarrangement may also increase the blower's 4142 efficiency by reducingthe length of the flow path between the blower 4142 and the patient,i.e., through the plenum chamber, as a result of a reduction in pressurelosses and leak.

In another alternative, the RPT system may be vented with anelectronically actuated vent or a pneumatically actuated vent to improveefficiency of the RPT system, e.g., the blower 4142, by reducingunnecessary vent leak and reducing the length of the flow path. Suitableexamples of electronically actuated vents may be found in PCT PatentApplication Publication No. WO 2013040198.

As described above, the upper housing portion 4132 of the examples shownin FIGS. 16A-16C and 17 may include a vent assembly 3400. The ventassembly 3400 may simply comprise a number of holes through one or moresides of the upper housing portion 4132 that are always open regardlessof the patient's breath phase and/or the operation of the blower 4142.In other words, the vent assembly 3400 continuously allows gas to exitthe plenum chamber 3200. Alternatively, the vent assembly 3400 mayfacilitate selective venting, e.g., based on the phase of the patient'sbreathing and/or the operation of the blower 4142.

The vent assembly 3400 shown in FIGS. 18A-18H provides this selectiveventing. The vent assembly 3400 may include a base 3404. The base 3404may be attached to the upper housing portion 4132 permanently orremovably (e.g., for replacement or cleaning), or the upper housingportion 4132 may form the base 3404.

The base 3404 may include a vent hole extension 3403 extending from thebase 3404. In the depicted examples, two vent hole extensions 3403 areincluded, one on each lateral side of the base 3404. Each vent holeextension 3403 may include an exterior vent hole surface 3401 that facestowards or is adjacent to atmosphere or faces away from the plenumchamber 3200. Each vent hole extension 3403 may also include an interiorvent hole surface 3407 that faces or is adjacent to the plenum chamber3200. Each vent hole extension 3403 may also include an internal surface3408. In cross-section, the vent hole extension 3403 may have agenerally triangular shape with the exterior vent hole surface 3401, theinterior vent hole surface 3407, and the internal surface 3408 formingeach side of the triangle. However, it should be understood that each ofthese surfaces may be flat or curved (convex or concave). Each vent holeextension 3403 may include one or more vent holes 3402 passing betweenthe interior vent hole surface 3407 and the exterior vent hole surface3401. The vent hole(s) 3402 may follow a linear path or a non-linearpath through the vent hole extension 3403. The vent hole(s) 3402 permitgas to pass therethrough to atmosphere during venting, as will bedescribed below.

The vent assembly 3400 may also include a divider 3406 that separatingthe vent assembly 3400 into two halves. Additionally, a flexiblemembrane or flap 3405 may be attached to each vent hole extension 3403that may cover the vent hole(s) 3402 during the inhalation phase toprevent pressurized from being discharged to atmosphere, therebyreducing pressure within the plenum chamber 3200. The flexible membrane3405 may be relatively thin and may be elastically deformable due to airpressure. The flexible membrane 3405 may be formed from an elasticallydeformable material such as liquid silicone rubber. The flexiblemembrane 3405 may be permanently attached to the interior vent holesurface 3407 of the vent hole extension 3403 by an adhesive or byovermolding. The flexible membrane 3405 may be cantilevered to theinterior vent hole surface 3407 of the vent hole extension 3403 to allowthe flexible membrane 3405 to cover the vent hole(s) 3402.

Additionally, the interior vent hole surface 3407 is angled in thedirection of the flow of pressurized gas from the blower 4142 such thatit is biased into a closed position. However, by virtue of itscantilevered attachment to the interior vent hole surface 3407 of thevent hole extension 3403, a relatively low magnitude of flow from thepatient's exhalation can force the flexible membrane 3405 into aposition that opens the vent holes 3402 to atmosphere.

The divider 3406 is shown as a rectangular prism in the depictedexamples. However, the divider 3406 may have sloped or curved sidesfacing the corresponding vent hole extensions 3403.

Also, the flexible membranes 3405 are dimensioned in a longitudinaldirection of the divider 3406 in the depicted examples such that theycover substantially all of the passages between the divider and the venthole extensions 3403. It should be understood that in alternativeexamples that the flexible membranes 3405 may not run substantially theentire width of the passages in a longitudinal direction of the divider.

Furthermore, the flexible membranes 3405 in the depicted examples areshown as a solid, continuous flap. However, the flexible membranes 3405may include one or more holes to allow tuning of the amount of flow thatthey permit.

Also, a flexible printed circuit board and/or wires for providing powerto and/or controlling the blower 4142 may pass through the divider 3406.

FIGS. 18F-18H depict operation of the vent assembly 3400. Although noneof the other RPT system components are shown, it should be understoodthat the vent assembly 3400 would be provided to the upper housingportion 4132 as described above in use. In each view, it should beunderstood that the blower 4142 is above the vent assembly 3400, andwhen producing the flow of pressurized gas, the flow will traveldownward through the vent assembly 3400 to the patient that is on theopposite side of the vent assembly 3400.

FIG. 18F shows the vent assembly 3400 in a neutral state in which thereis no air flow. Thus, the flexible membranes 3405 are in an undeformedstate. The flexible membranes 3405 are shown covering the vent holes3402 such that air cannot travel from the plenum chamber 3200 toatmosphere or vice versa. However, the flexible membranes 3405 may beattached to the vent hole extensions 3403 such that in an undeformedstate there is a slight gap between the flexible membranes 3405 and theinterior vent hole surface 3407 such that a small amount of flow ispermitted to travel through the vent holes 3402. Also, the flexiblemembranes 3405 may be dimensioned such that they do not engage thedivider 3406 in an undeformed state, as shown in FIG. 18F, to allow airflow to pass between the divider 3406 and the flexible membranes 3405.Alternatively, the flexible membranes 3405 may be dimensioned such thatthey do engage the divider 3406 in an undeformed state to prevent airflow from passing between the divider 3406 and the flexible membranes3405.

FIG. 18G shows the vent assembly 3400 during venting, e.g., duringpatient exhalation. FIG. 18G shows a vent flow 3409 coming from thedirection of the patient to displace and/or deform the flexiblemembranes 3405 such that the interior vent hole surface 3407 is exposedand the vent holes 3402 are opened or not blocked by the flexiblemembranes 3405. The vent flow 3409 may be generated by the force of thepatient's exhalation. By cantilevering the flexible membrane 3405 fromthe interior vent hole surface 3407 beyond the vent holes 3402 such thatthe flexible membrane 3405 overlays the vent holes 3402, the force ofthe vent flow 3409 will displace and/or deform the flexible membrane3405 thereby opening the vent holes 3402 such that the vent flow 3409can exit to atmosphere. The thickness and material of the flexiblemembrane 3405 may be selected such that the flexible membrane is readilydeformable enough to be displaced and/or deformed by the patient'sexhalation, even when being opposed by the flow from the blower 4142travelling in the opposite direction. Also, the flexible membranes 3405may be dimensioned such that they do not engage the divider 3406 duringthe exhalation phase, as shown in FIG. 18G, to allow air flow to passbetween the divider 3406 and the flexible membranes 3405. Alternatively,the flexible membranes 3405 may be dimensioned such that they do engagethe divider 3406 when deformed by exhalation to prevent air flow frompassing between the divider 3406 and the flexible membranes 3405 and toensure the full magnitude of the exhalation force is used to dischargegas, e.g., exhaled CO₂, to atmosphere.

FIG. 18H shows the vent assembly 3400 during the inhalation phase. Inthis view, a pressurized flow of gas 3410 from the blower 4142 pushesthe flexible membranes 3405 into a position against the interior venthole surface that closes off the vent holes 3402 such that thepressurized flow of gas 3410 is directed to the patient for inhalationand not lost to atmosphere. It should also be understood that theflexible membranes 3405 may occupy this position not just duringinhalation, but also at any point when the blower 4142 is generating thepressurized flow of gas 3410 and the patient is not exhaling. Thematerial and dimensions (e.g., thickness) of the flexible membrane 3405may be selected such that the pressurized flow of gas 3410 from theblower 4142 is sufficient to displace and/or deform the flexiblemembrane 3405 into a position that closes the vent holes 3402 opens thepassages between the divider 3406 and the vent hole extensions 3403 toallow the pressurized flow of gas 3410 to reach the patient. Also, theinterior vent hole surface 3407 may be angled such that it slopesinwardly or downwardly into the interior of the vent assembly 3400relative to the direction of the pressurized flow of gas 3410.

The vent assembly 3400 shown in FIGS. 18A-18H is advantageous in that itallows the vent holes 3402 to be opened or closed selectively dependingon the phase of the patient's breathing and/or the operation of theblower 4142, and the vent assembly does so passively. In other words,there is no need for a separately actuatable component to open and closevent holes, thereby reducing complexity. Also, vent assembly 3400 of thepresent technology permits cleaning by simply flushing the vent assembly3400 with water. The flexible membranes 3405 are sufficiently deformablefor water to displace them and allow cleaning throughout. Furthermore,the absence of additional, complex actuating components means that watercan readily be flushed through the vent assembly 3400 without damagingit.

The vent assembly 3400 may also include a diffuser material at theexterior vent hole surface 3401 to diffuse the flow of gas passing toatmosphere from the vent hole(s) 3402 to reduce noise and jetting.

Other vent arrangements are also envisioned for application to thepresent technology. For example, the vent arrangements disclosed inFIGS. 33-35 of U.S. Patent Application Publication No. US 2014/0305431A1 may also be incorporated into the RPT system of the presenttechnology.

5.3.5 Connection Port

In one form the patient interface 3000 comprises a connection port 3600for connection to the air circuit 4170.

5.3.6 Forehead Support

In one form, the patient interface 3000 includes a forehead support3700. The example of the present technology depicted in FIGS. 6A-6C doesnot include a forehead support. Although a forehead support is not shownin the example depicted in FIGS. 6A-6C, a forehead support may beincorporated into the RPT system, e.g., as a part of the plenum chamber3200 extending therefrom. The forehead support may be added to enhancestability of the RPT system on the patient's head in use by addinganother separate point of contact.

5.3.7 Anti-Asphyxia Valve

In one form, the patient interface 3000 includes an anti-asphyxia valve.

5.3.8 Ports

In one form of the present technology, a patient interface 3000 includesone or more ports that allow access to the volume within the plenumchamber 3200. In one form this allows a clinician to supply supplementaloxygen. In one form, this allows for the direct measurement of aproperty of gases within the plenum chamber 3200, such as the pressure.

The plenum chamber 3200 may also comprise a port 4134 that is configuredto be connected to at least one of a pressure transducer and asupplemental gas source. The pressure transducer, as described ingreater detail below, may provide data regarding the conditions withinthe plenum chamber during operation that can be used by the controlsystems for controlling the blower 4142. The supplemental gas source mayprovide the patient with supplemental oxygen, for example, as prescribedby a clinician.

5.4 RPT Device

An RPT device 4000 in accordance with one aspect of the presenttechnology comprises mechanical, pneumatic, and/or electrical componentsand is configured to execute one or more algorithms. The RPT device 4000may be configured to generate a flow of air for delivery to a patient'sairways, such as to treat one or more of the respiratory conditionsdescribed elsewhere in the present document.

In one form, the RPT device 4000 is constructed and arranged to becapable of delivering a flow of air in a range of −20 L/min to +150L/min while maintaining a positive pressure of at least 6 cmH₂O, or atleast 10cmH₂O, or at least 20 cmH₂O. In another form, the RPT device4000 may be constructed and arranged to be capable of delivering a flowof air in a range of −60 L/min to +80 L/min while maintaining a positivepressure of at least 6 cmH₂O, or at least 10cmH₂O, or at least 20 cmH₂O.

The pneumatic path of the RPT device 4000 may comprise one or more airpath items, e.g., an inlet air filter 4112, an inlet muffler 4122, apressure generator 4140 capable of supplying air at positive pressure(e.g., a blower 4142), an outlet muffler 4124 and one or moretransducers 4270, such as pressure sensors 4272 and flow rate sensors4274.

One or more of the air path items may be located within a removableunitary structure which will be referred to as a pneumatic block 4020.The pneumatic block 4020 may be located within the external housing4010. In one form a pneumatic block 4020 is supported by, or formed aspart of the chassis 4016.

The RPT device 4000 may have an electrical power supply 4210, one ormore input devices 4220, a central controller 4230, a therapy devicecontroller 4240, a pressure generator 4140, one or more protectioncircuits 4250, memory 4260, transducers 4270, data communicationinterface 4280 and one or more output devices 4290. Electricalcomponents 4200 may be mounted on a single Printed Circuit BoardAssembly (PCBA) 4202. In an alternative form, the RPT device 4000 mayinclude more than one PCBA 4202.

5.4.1 RPT Device Mechanical & Pneumatic Components

An RPT device may comprise one or more of the following components in anintegral unit. In an alternative form, one or more of the followingcomponents may be located as respective separate units. The RPT devicemay include one or more pneumatic components 4100.

An RPT device in accordance with one form of the present technology mayinclude one or more air filters 4110, and/or one or more mufflers 4120.

5.4.1.1 Pressure Generator

In one form of the present technology, a pressure generator 4140 forproducing a flow, or a supply, of air at positive pressure is acontrollable blower 4142. For example the blower 4142 may include abrushless DC motor 4145 with one or more impellers housed in a volute.In another example, blower 4142 may include a brushless DC motor 4145with one or more impellers and stator vanes, and housed in a casing. Theblower may be capable of delivering a supply of air, for example at arate of up to about 120 litres/minute, at a positive pressure in a rangefrom about 4 cmH₂O to about 20 cmH₂O, or in other forms up to about 30cmH₂O. The blower may be as described in any one of the followingpatents or patent applications the contents of which are incorporatedherein by reference in their entirety: U.S. Pat. Nos. 7,866,944;8,638,014; 8,636,479; and PCT Patent Application Publication No. WO2013/020167.

The pressure generator 4140 is under the control of the therapy devicecontroller 4240.

In other forms, a pressure generator 4140 may be a piston-driven pump, apressure regulator connected to a high pressure source (e.g. compressedair reservoir), or a bellows.

5.4.1.1.1 Blower 4142 of the Present Technology

The blower 4142 of the present technology may include multiple sets ofstages of small diameter impellers in parallel flow paths. The parallelstage arrangement may allow the blower 4142 to generate sufficient flowrates, while reducing the size of the blower 4142 and reducing itsgeneration of noise. As can be seen in FIGS. 7A-7F, the exemplary blower4142 includes two sets of a first compression stage 4136 and a secondcompression stage 4137, wherein each set is arranged in parallel on eachside of a motor 4145. In other words, the blower 4142 may include twopairs of stages in a substantially mirrored configuration relative to anaxial direction of the motor 4145. While the exemplary blower 4142 isshown with two stages arranged in series on each side, it is envisionedthat there could be only one stage on each side of the blower 4142.Alternatively, there could be more than two compression stages providedto each side of the blower. In still further alternatives, there couldbe asymmetric compression stages, e.g., one stage on one side of theblower 4142 and two stages on the other side of the blower 4142. Thestages themselves may also be asymmetric in that the stator and impellerof any given stage may be distinct from those of another stage.

The blower 4142 may be used in a respiratory pressure therapy (RPT)system and may be configured to generate a flow of air at a therapeuticpressure of at least 6 cmH₂O above ambient air pressure. The exemplaryblower 4142 and RPT systems disclosed in FIGS. 6A to 14 may be used totreat sleep disordered breathing conditions such as sleep apnea and mayalso be used to treat other respiratory issues not necessarily relatedto sleep such as COPD. The blower 4142 may comprise a motor 4145 havinga first end and a second end (shown in a simplified outline form). Theblower 4142 may also have a generally cylindrical shape. Also, a firstimpeller 4150 and a second impeller 4160 may be arranged in series onthe shaft 4146 such that both first impellers 4150 and both secondimpellers 4160 are driven simultaneously by the motor 4145.

As each set of impellers at either end of the motor 4145 are configuredto generate a flow of gas in opposing directions to each other, whilebeing driven by the same shaft, each opposing impeller 4150 and 4160 maycomprise a mirrored geometry. Thus, for example, impellers 4150, 4160located at a first end of the shaft 4146 of the motor 4145 may eachcomprise forward swept blades and impellers 4150, 4160 located at thesecond or opposite end of the shaft 4146 of the motor 4145 may have adifferent (mirrored) geometry. In other words, since both ends of theshaft 4146 will be rotating in the same direction when the motor 4145 isoperating, the impellers 4150, 4160 at each respective end of the shaftmay be swept forward relative to the shaft's 4146 rotational directionso that both sides of the blower 4142 generate a flow of gas in the samedirection.

The blower 4142 may also include a first stator 4180 corresponding toeach of the first end of the motor 4145 and the second end of the motor4145. The first stator 4180 may be positioned downstream of the firstimpeller 4150 and upstream of the second impeller 4160 along the flow ofair generated by the blower in use. The blower 4142 may also include asecond stator 4190 corresponding to each of the first end of the motor4145 and the second end of the motor 4145, the second stator 4190positioned downstream of the second impeller 4160 along the flow of airgenerated by the blower 4142 in use.

The blower 4142 may also include an end cap 4144 that is shaped anddimensioned to at least partially enclose each first impeller 4150. Eachend cap 4144 may also at least partially define a blower inlet 4143 oneach side of the blower 4142. The blower 4142 may also include a bloweroutlet 4141 positioned downstream of each second stator, such as at ortowards a centre of the blower 4142 in the axial direction. A flow path4138 for the flow of air passing from each blower inlet 4143, past eachfirst impeller 4150, through each first stator 4180, past each secondimpeller 4160, through each second stator 4190, and out each bloweroutlet 4141 may be defined through the blower 4142. The blower outlet4141 may extend annularly around the entirety or a portion of thecircumference of the blower 4142.

FIG. 7A depicts an example of the blower 4142 according to the presenttechnology separated from the housing portions 4132, 4133. For example,the mounting rails 4183 on the exterior of the first stator housing 4184of the first stator 4180 are visible. Also, the blower outlet 4141 isvisible, as well as a portion of the second stator 4190 that leads tothe blower outlet 4141. FIG. 7A also depicts other components of theblower 4142, including the end cap 4144, which defines the blower inlet4143 and partially encloses the first impeller 4150. As can be seen inFIG. 7A, the blower's 4142 structure is mirrored or symmetrical suchthat each half of the blower 4142 may include identical (mirrored)components.

Thus, the blower 4142 may comprise two sets of inlets and outlets. Thatis, a set of inlets 4143 (e.g. two inlets) located at or toward opposingends of the blower 4142, and a set of outlets 4141 (e.g. two outlets)located at or towards a centre of the blower 4142, with respect to anaxial direction of the blower 4142.

FIG. 7B depicts a similar view of the exemplary blower 4142 to FIG. 7A,but the end caps 4144 are removed to depict the first impellers 4150.Additionally, a portion of the first stator vanes 4186, 4187 of thefirst stator 4180 are also visible. As will be described in greaterdetail below, during the first compression stage the flow of gasgenerated by spinning the first impeller 4150 passes within the volumedefined by the end cap 4144 and then through the first stator vanes4186, 4187 to reach the second impeller 4160 for the second stage ofcompression.

FIG. 7C depicts another view of the exemplary blower 4142 with the endcaps 4144 and the first impellers 4150 such that the first stator uppershroud 4182A of the first stator 4180 is visible. Additionally, a largerportion of the first stator vanes 4186, 4187 are visible as well. Duringthe first stage of compression 4136, the flow of gas generated byspinning the first impeller 4150 passes under the first stator uppershroud 4182A and between the first stator vanes 4186, 4187 beforereaching the second impeller 4160 for the second stage of compression4137.

FIG. 7D depicts another view of the exemplary blower 4142 with the firststator 4180 removed. In this view, the second impeller 4160 and thesecond stator 4190, including the second stator vanes 4191, are morefully visible. The features of these individual components will bedescribed in greater detail below.

FIG. 7E depicts a cross-sectional view of the exemplary blower 4142, asshown in FIG. 7A, in which the cross-section is cut along a planecontaining the axis of rotation of the motor 4145. In this view, it ispossible to see portions of the flow path that gas follows from theblower inlet 4143 through both stages of compression and out the bloweroutlet 4141.

FIG. 7F depicts an exploded view of the exemplary blower 4142.

5.4.1.1.1.1 Compression Stages 4136, 4137

In one exemplary configuration, each pair of compression stages 4136,4137 corresponding to two impeller-stator pairs, could deliver up toapproximately 40 L/min of flow with the motor 4145 operating at, e.g.,65,000 rpm. Thus, combining the pairs of compression stages 4136, 4137in parallel on each side of the blower 4142 would be capable ofdelivering approximately 80 L/min at a therapeutic pressure ofapproximately 10 or 15 cmH₂O. In this example, the motor 4145 would havean outer diameter of 13 mm and a length of 37 mm and the blower 4142would have an outer diameter of 18 mm and a length of 46 mm. It is alsoenvisioned that additional impellers could be added in series to anindividual compression stage to generate even higher pressures.

5.4.1.1.1.2 Motor 4145

The blower 4142 may include a motor 4145 in the form of a singlebrushless DC motor. The motor 4145 may include a shaft 4146 protrudingfrom each end in an axial direction to drive the corresponding impellerson each side. Since the ends of the shaft 4146 would spin in samedirection during operation of the blower 4142, it should be understoodthat the shapes of the impellers and stators may be mirrored butotherwise identical on opposite sides of the blower 4142. The motor 4145of the present technology may be capable of operating from a minimum ofapproximately 5,000 rpm or approximately 10,000 rpm to a maximum ofapproximately 50,000 rpm to approximately 80,000 rpm, generating maxtorque from approximately 0.5 mN-m to approximately 1 mN-m, andgenerating max power of approximately 3 W to 6 W. While the depictedexample includes one motor to drive both sets of compression stages4136, 4137 on each side of the blower 4142, it is envisioned that theblower 4142 could include two motors 4145 in which each motor drives asingle set of the compression stages 4136, 4137.

5.4.1.1.1.3 Impellers 4150, 4160

An exemplary first impeller 4150 is depicted in FIGS. 8A-8L, but itshould be understood that each second impeller 4160 may be identical tothe corresponding first impeller 4150. Alternatively, each firstimpeller 4150 and each second impeller 4160 may be designeddistinctively to optimize the flow rate and pressure generated based ontheir relative positions in the flow path 4138. Regardless of whetherthey are designed differently or identically, each first impeller 4150and each second impeller 4160 may include an impeller hub 4153, impellervanes 4151 extending radially from the impeller hub 4153, and animpeller shroud 4152. The impeller hub 4153 is the portion of theimpeller 4150 that joins the impeller 4150 to the corresponding end ofthe shaft 4146.

The impeller vanes 4151 direct the flow of gas radially outward duringrotation of the impeller 4150. The impeller vanes 4151 may each have afirst impeller vane portion 4154 that extends only in a radial directionand a second impeller vane portion 4155 that extends in a radial,tangential and axial direction (or in a radial and axial directiononly). The first impeller vane portion 4154 may have a constantcross-section and the first impeller vane portion 4154 may be positionedis radially inward relative to the second impeller vane portion 4155.The second impeller vane portion 4155 may have a variable cross-sectionand may be positioned radially outward relative to the first impellervane portion 4154. The constant cross-section of the first impeller vaneportion 4154 may also be thinner than the variable cross-section of thesecond impeller vane portion 4155 at any point. The variablecross-section of the second impeller vane portion 4155 may increase inthickness radially outward from the first impeller vane portion 4154 andthen decrease in thickness further radially outward.

The impeller vanes 4151 of each first impeller 4150 and each secondimpeller 4160 may be swept or curved forward relative to the directionof rotation 4139 during operation. Alternatively, the impeller vanes4151 of each first impeller 4150 and each second impeller 4160 may beswept or curved backward relative to the direction of rotation 4139during operation.

The impeller shroud 4152 prevents the incoming flow of gas fromtraveling past the impeller vanes 4151 in an axial direction so that theimpeller vanes 4151 redirect the flow of gas radially, while spinningthe gas tangentially. Each impeller shroud 4152 may include a firstimpeller shroud portion 4156 that extends only in a radial direction anda second impeller shroud portion 4157 that extends in a radial and axialdirection. The impeller shroud 4152 may also include cutouts to allowmoulding of the impellers in the line of draw.

The first impeller vane portion 4154 of the impeller 4150 shown in FIGS.8A to 8M may be straight to maximise its cross-sectional area, therebyminimising entry loss at the blower inlet 4143. Indeed, as can be seenin FIG. 7A, the first impeller vane portion 4154 is exposed through theblower inlet 4143 to draw in air. Furthermore, the forward curvature ofthe second impeller vane portion 4155 may create pressure throughrelatively high tangential velocities. Additionally, axial developmentof the flow out of the impeller 4150 in the axial direction mayencourage the flow to travel in the axial direction, which maybeneficially add axial velocity that the stators 4180, 4190 can convertinto additional pressure. The concept of additional axial developmentmay be understood to mean that the more time that the airflow spendswhere work is being done on it by the impeller 4150 (e.g., viacentrifugal effects), the more the stators 4180, 4190 can convert theincreased velocity of the airflow into pressure. Additional axialdevelopment also means more time that the air flow spends where work isbeing done on it by the impeller 4150 (hence generating pressure viacentrifugal effects).

FIGS. 12A and 12B depict another example of the first impeller 4150according to the present technology. This first impeller 4150 is similarto the first impeller 4150 described above in that it includes the samebasic structural components, e.g., first impeller vanes 4151, the firstimpeller shroud 4152, and the first impeller hub 4153. However, thefirst impeller vanes 4151 and the first impeller shroud 4152 are shapeddifferently in the example of FIGS. 12A and 12B. For example, thecross-section of the first impeller vanes 4151 does not change inthickness in a radial direction between the first impeller vane portions4154 and the second impeller vane portions 4155. Also, the curvature ofthe second impeller vane portions 4155 is more abrupt in the example ofFIGS. 12A and 12B. Furthermore, the second impeller vane portions 4155do not extend in an axial direction in the example of FIGS. 12A and 12B.Similarly, the first impeller shroud 4152 does not extend from the firstimpeller hub 4153 in an axial direction in the example of FIGS. 12A and12B. In other words, the first impeller shroud 4152 is generally flat,at least on the side opposite the first impeller vanes 4151. Theimpeller vanes 4151 of the impeller 4150 of FIGS. 12A and 12B may beswept or curved forward relative to the direction of rotation 4139during operation. Alternatively, the impeller vanes 4151 of the impeller4150 of FIGS. 12A and 12B may be swept or curved backward relative tothe direction of rotation 4139 during operation.

The exemplary first impeller 4150 depicted in FIGS. 13A and 13B issimilar to the first impeller 4150 depicted in FIGS. 12A and 12B, exceptfor the shape of the first impeller vanes 4151. In the exemplary firstimpeller 4150 of FIGS. 13A and 13B the first impeller vanes 4151 have acontinuous and less abrupt curvature in the radial direction. However,like the first impeller 4150 of FIGS. 12A and 12B, the first impeller4150 of FIGS. 13A and 13B, the thickness of the cross-section of thefirst impeller vanes 4151 is consistent in the radial direction. Theimpeller vanes 4151 of the impeller 4150 of FIGS. 13A and 13B may beswept or curved forward relative to the direction of rotation 4139during operation. Alternatively, the impeller vanes 4151 of the impeller4150 of FIGS. 13A and 13B may be swept or curved backward relative tothe direction of rotation 4139 during operation. As described above,either of the first impellers 4150 depicted in FIGS. 12A and 12B orFIGS. 13A and 13B could be used in both the first compression stage 4136and the second compression stage 4137. In other words, both compressionstages 4136, 4137 include identical impellers for the first impeller4150 and the second impeller 4160. Alternatively, different impellerdesigns may be used in each of the first compression stage 4136 and thesecond compression stage 4137.

The first impeller vane portion 4154 of the impeller 4150 shown in FIGS.12A and 12B may be straight to maximise its cross-sectional area,thereby minimising entry loss at the blower inlet 4143. Indeed, as canbe seen in FIG. 7A, the first impeller vane portion 4154 is exposedthrough the blower inlet 4143 to draw in air. Furthermore, the forwardcurvature of the second impeller vane portion 4155 may create pressurethrough relatively high tangential velocities.

5.4.1.1.1.4 Impeller 500

Examples of impellers according to the present technology are shown inFIGS. 19A-19EE. The impeller may be suitable for use in a centrifugalblower, such as those described elsewhere in the present specification.

An impeller 500 may comprise one or more of:

-   -   a set of impeller blades 510, each impeller blade 510 comprising        a leading edge 511 and a trailing edge 512;    -   a first shroud and/or a second shroud, such as a top shroud 520        and/or a bottom shroud 525, at least partly defining a flow        passage 540 through the impeller;    -   a hub 530 for coupling the impeller to a motor, the hub 530 may        be retained by an interference fit to a rotor or motor shaft of        the motor for example, however any number of other known        retention mechanisms may be suitable.

Where the impeller 500 comprises a first shroud and a second shroud, thefirst and second shrouds may be arranged such that an axial distancetherebetween may generally decrease towards an outer portion of theimpeller in the radial direction.

FIGS. 19A to 19N illustrate an impeller 500 according to one example ofthe present technology. As illustrated, the impeller 500 includes aplurality of impeller blades 510 located between and connected to thefirst or top shroud 520 and the second or bottom shroud 525. In theillustrated example, the bottom shroud 525 extends to the hub 530adapted to receive the rotor of the motor.

In the illustrated example, the top shroud 520 is substantiallynon-planar. For example, the top shroud 520 may taper in the radialdirection with respect to the axial direction of the impeller, e.g., thetop shroud 520 may comprise a frusto-conical shape. The top shroud 520includes an outer edge defining a diameter D of the top shroud and aninner edge defining a center opening which provides an impeller inlet522. An impeller inlet wall 521 extends along the inner edge to define aperiphery of the impeller inlet 522. The free end portion of the inletwall 521 provides a leading edge 523 of the impeller inlet 522. In thisarrangement, the top shroud 520 extends to an outer periphery of theimpeller, thus the diameter D of the top shroud is the same as thediameter of the impeller. However in other arrangements, the top shroud520 may not extend to the outer periphery of the impeller, for exampleonly covering a part of the impeller blades.

In the illustrated example, the bottom shroud 525 is substantiallyplanar. As illustrated, the outer edge of the bottom shroud 525 definesa diameter that is substantially similar, e.g., the same, to thediameter D defined by the outer edge of the top shroud 520. In anexample, the diameter D of the impeller is less than about 50 mm.

The top and bottom shrouds 520, 525 cooperate to define a flow passage540 therebetween through the impeller. The flow passage 540 extends fromthe impeller inlet 522 at an inner portion of the impeller to animpeller outlet 524 at an outer portion of the impeller. The flowpassage 540 may include a plurality of channels, each channel defined atleast partly by the top and bottom shrouds 520, 525 and impeller blades510.

In the illustrated example, the flow passage 540 defined between the topand bottom shrouds 520, 525 is structured to narrow (in a normaldirection to the direction of the airflow) from the impeller inlet 522to the impeller outlet 524, i.e., the spacing or distance between thetop and bottom shrouds 520, 525 lessens or tapers from the impellerinlet to the impeller outlet.

That is, the top and bottom shrouds 520, 525 are configured such thatthe flow passage is narrower in the axial direction at the outer portionof the impeller than at the inner portion of the impeller, i.e., anaxial distance between the top and bottom shrouds 520, 525 may generallydecrease towards the outer portion of the impeller in the radialdirection. For example, FIG. 19B shows exemplary axial distances d1 andd2 between the top and bottom shrouds 520, 525, with d1 along an innerportion of the impeller larger than d2 along an outer portion of theimpeller and the axial distance gradually decreasing from d1 to d2 inthe radial direction. Additionally, the top and bottom shrouds 520, 525are configured such that the axial distance between them at the outletof the impeller (i.e., d2) is smaller than the radial dimension of theinlet.

Thus, an impeller according to an aspect of the present technology maycomprise a flow passage 540 comprising a plurality of channels, eachchannel configured with a decreasing height along a direction of the airflow therethrough.

5.4.1.1.1.4.1 Impeller Inlet

An impeller according to the present technology may comprise arelatively large impeller inlet size as a proportion of the impellerdiameter D. In one form, the impeller inlet 522 may be defined by aperiphery of the top shroud 520, such as in FIG. 19B, where the inletwall 521 of the top shroud 520 is shown in the cross section.

In general, it may be a disadvantage to increase a size of the impellerinlet in a centrifugal blower while maintaining other dimensions (e.g.,impeller diameter), as such an increase may decrease an effectivediameter of the impeller in which centrifugal energy may be imparted tothe air flowing through the blower. In other words, enlargement of animpeller inlet may result in a configuration wherein insufficientpressure is generated by the blower.

However, for an application such as in RPT devices, where a small sizeof the device is desirable for aesthetic reasons, convenient bedsideplacement of the RPT device and portability, a designer may wish toreduce a size of the impeller. However, as an impeller diameter isreduced, a velocity of the air flow through the impeller is increased,adversely affecting noise and efficiency of the impeller, for examplecaused by changes to an aerodynamic behaviour due to the increase in airvelocity.

As described elsewhere, an RPT device may be relatively unique in thatit is preferably small and quiet for bedside/nocturnal/sleep-time use,while requiring generation of sufficient pressures and flow rates forrespiratory therapy. For use in small, possibly portable, RPT devices,it was found that a decrease in impeller diameter may be accompanied bya relative increase in the impeller inlet diameter.

In one form, the impeller of a diameter D of less than 50 mm maycomprise an impeller inlet 522, wherein a diameter (d_(inlet) as shownin FIG. 19A) of the impeller inlet 522 is at least 50% of the diameter Dof the impeller. In one example, the impeller may comprise a diameter Dof 40 mm with an impeller inlet diameter d_(inlet) of 20 mm, 22 mm or 24mm.

According to another aspect of the present technology, the impellerinlet wall 521, or a periphery of the impeller inlet 522, may comprise arelatively large radius to improve overall impeller and/or blowerperformance. An increased radius at a portion facing the incoming airflow into the impeller may advantageously lead to improved efficiency,as the air flow remains attached to the inlet wall 521.

In one form, a leading edge of the periphery of the impeller inlet 522,e.g., the leading edge 523 at the free end portion of the inlet wall 521of the top shroud 520 (as best shown in FIG. 19B), comprises a crosssectional shape with a radius of at least 0.5 mm. In another form, aradius of the leading edge of the first or top shroud 520 is greaterthan 70% of the maximum thickness of the body of the first shroud 520,such as greater than 85%, 100% or 115%. In another form, a radius of theleading edge 523 of the first or top shroud 520 is greater than themaximum thickness of a body of the first shroud 520. In another form, aleading edge of the first or top shroud 520 comprises a cross sectionalshape with a radius of at least 1% of the diameter D of the impeller. Inuse, an air flow entering the impeller at the impeller inlet 522 isdiscouraged from detachment at or around the radius, e.g., to reducenoise and improve efficiency.

5.4.1.1.1.4.2 Impeller Blades

The impeller 500 may comprise a plurality of impeller blades 510. In theillustrated example, the impeller includes 11 blades 510. However, itshould be appreciated that the impeller may include other suitablenumbers of blades, e.g., 3 or more blades, e.g., 5-20 blades, e.g., 7blades, 11 blades, 13 blades.

Each impeller blade 510 extends from the hub 530 towards the outer edgeof the impeller. Each impeller blade may be connected to the top andbottom shrouds 520, 525. Each impeller blade comprises a leading edge511 and a trailing edge 512. It should be noted that the terms ‘leadingedge’ and ‘trailing edge’ are to be understood akin to its usage inaeronautics, referring to a portions of a wing, rather than a narrowgeometric sense of an ‘edge’.

For example, a ‘leading edge’ may refer to a part of the impeller bladethat generally first contacts the air coming into the impeller.Similarly, a ‘trailing edge’ may refer to a part of the impeller bladethat generally last contacts the air as it leaves the impeller.

In the illustrated example, the impeller blades 510 are sandwichedbetween the top and bottom shrouds 520, 525. As illustrated, each blade510 is overlapped by the top shroud 520 such that a first edge 515 alongan outer portion of the blade is in contact with the top shroud 520 andthe leading edge 511 along an inner portion of the blade is exposedthrough the impeller inlet 522, i.e., leading edge 511 extends betweenthe inlet wall 521 and the hub 530 defining the inlet 522 into theimpeller. Each blade 510 is overlapped by the bottom shroud 525 suchthat a second edge 517 is in contact with the bottom shroud 525 and hub530 along its entire length. The trailing edge 512 is exposed throughthe impeller outlet 524 between the outer ends of the top and bottomshrouds 520, 525.

In the illustrated example, each blade 510 extends to the outer edges ofthe top and bottom shrouds 520, 525, e.g., the blades 510 do not extendbeyond the top and bottom shrouds 520, 525. In alternative examples, theblades 510 may extend beyond or extend short of the outer edges of thetop and bottom shrouds 520, 525.

According to one aspect of the present technology, the leading edge 511and/or the trailing edge 512 of an impeller blade 510 may be very thin,such that turbulence and noise is reduced at the inlet and outlet of theimpeller. In an example, the thickness of the leading edge 511 and/orthe trailing edge 512 of an impeller blade 510 may be less than about0.2 mm, e.g., less than about 0.1 mm, such as measured at its thinnestportion, or measured at its outermost portion (i.e., most downstreamportion). Furthermore, uniquely to RPT devices, some impeller designsmay be such that a seemingly small reduction in a size of the leading(and/or trailing) edge may have a positive effect on the air flow of theimpeller and efficiency of the RPT device.

In an example, the cross-sectional thickness of each blade 510 may bevariable or tapered, e.g., along at least a portion of its length inplan view. For example, as shown in FIGS. 19K-19N, an outer portion ofeach blade 510 may include a cross-sectional thickness that taperstowards the trailing edge 512.

Also, as shown in FIGS. 19K-19N, each blade 510 may be curved and/orprovide curved exterior surfaces, e.g., along at least a portion of itslength in plan view. For example, as shown in FIGS. 19K-19N, an outerportion of each blade 510 may provide curved surfaces 519 along itslength towards the trailing edge 512, e.g., to provide a smooth air flowpassage to reduce turbulence and hence noise.

Further, as shown in FIGS. 19K-19N, the flow passage defined betweenadjacent blades 510 is structured to enlarge, e.g., along at least aportion of its length in plan view. For example, as shown in FIGS.19K-19N, the flow passage defined between adjacent blades 510 isstructured to enlarge towards the trailing edges 512, e.g., to increasepressure.

An impeller blade 510 may be inclined, as shown in FIGS. 19C, 19P or thecross sections shown in FIGS. 19K-19N. For example, the leading edge 511of each blade 510 may be inclined, e.g., by an angle greater than 45degrees, with respect to an axis of the hub 530 or motor.

In the example of FIGS. 19A-19N, the trailing edge 512 extendssubstantially parallel to an axis of the hub 530.

In some forms, as shown in FIGS. 19O-19S, the impeller blade 510 maycomprise one or more serrations, e.g., the leading edge 511 and/or thetrailing edge 512 may comprise one or more serrations arranged along theleading edge 511 and/or the trailing edge 512. Some examples ofpotentially suitable arrangements of leading edge and/or trailing edgeserrations may be found on PCT Patent Application Publication No. WO2016/201516, the contents of which is incorporated herein by referencein its entirety.

5.4.1.1.1.4.3 Impeller Construction

Many prior art impellers, particularly in the field of respiratorypressure therapy devices, have been manufactured by injection moulding apolymer material. Typical reasons may have included (but not limitedto):

-   -   low cost per part, particularly as volume produced increases;    -   smooth surface finish from injection moulding, which may        minimise any turbulence generated;    -   high reproducibility of moulded parts, ensuring consistency and        quality control; and    -   low density (and relatively high stiffness and strength) of        plastic used, helping to minimise mass and rotational inertia,        such that rapid acceleration and deceleration may be more easily        achievable.

As a consequence of using injection moulding, particular impellergeometries may have been either extremely difficult to achieve, orsimply not possible using injection moulding only. For example, animpeller employing curved and swept blades, as well as top and bottomshrouds, may be extremely difficult to manufacture using an injectionmoulding process. That is, once the component had been moulded, it couldnot be extracted from the moulding tool, as the tool and the componentwould now be intertwined.

In another example, an injection moulded plastic component may require aminimum wall thickness, such that the molten plastic being injected maybe able to flow sufficiently within the mould without requiringexcessive pressures.

In some examples, an impeller comprising one or more of the aspectsdescribed herein may be manufactured by employing alternativemanufacturing methods or constructions, while overcoming some of thedisadvantages previously associated with such methods.

Additive Manufacturing

In one aspect, an impeller according to the present technology may beproduced by an additive technique, sometimes referred to as“three-dimensional (3D) printing”, potentially using a metallic materialsuch as titanium, aluminium or stainless steel.

In many applications, even in some instances of RPT devices, a metallicimpeller may have a disadvantage over a polymer impeller due to theincreased rotational inertia. As alluded to earlier, a higher rotationalinertia of an impeller may require an increased capability from a motordriving the impeller, as the requisite torque to accelerate ordecelerate the impeller is increased. In turn, the motor may increase insize, and requirements for the power supply and/or a battery mayaccordingly be increased.

However, for a relatively small impeller, some of these problems may beameliorated, whereby use of a metallic material becomes more feasible.As a diameter of the impeller decreases, the corresponding rotationalinertia decreases as a power of 4 of a decrease of diameter, as: 1≈mr²,where I refers to rotational inertia, m to mass of the impeller and r isthe radius of the impeller.

Thus, advantageously, it was found that for the present application andsize, additive manufacturing techniques using a metallic material may beparticularly suitable such that high-efficiency geometry such as thosedescribed herein may be achieved.

In some instances, a material (e.g., metallic material) with thesame/similar coefficient of expansion as a rotor (e.g., motor shaft) maybe chosen (e.g., the shaft and the impeller may comprise the same metalor metallic material), such that if the impeller is press fit onto therotor, any thermal expansion would occur uniformly between the twojoined, rotating components. This may help to preserve integrity of aninterference fit despite variations in temperature, which may vary morewithin a motor than for example in ambient air.

Multi-Part Construction

According to one aspect of the present technology, such as shown inFIGS. 19T-19EE, an impeller 500 may comprise multiple portions.

In some forms, one portion may comprise a different material to anotherportion. For instance, a first portion may comprise a deformable,resilient material and a second portion may comprise a rigid material.In an example, the rigid material may be a plastic material, and theresilient material may be an elastomeric material such as a siliconematerial.

In the example shown in FIGS. 19Y-19EE, a first moulded part or portion,i.e., a first impeller portion 500-1, may be structured and arranged tobe coupled to a second moulded part or portion, i.e., second impellerportion 500-2, to produce the impeller 500. The first impeller portion500-1 may comprise a deformable, resilient material (e.g., anelastomeric material such as silicone) that may be coupled with thesecond impeller portion 500-2 comprising a rigid material (e.g., rigidplastic). For example, a manufacturing process may first produce (e.g.,mould) the second impeller portion 500-2, onto which the first impellerportion 500-1 may be overmoulded. Other forms of coupling, such aschemical bonding or mechanical bonding, may be suitable that are notovermoulded.

As illustrated, the first impeller portion 500-1 comprises the pluralityof impeller blades 510, a portion of the top shroud 520 (i.e., an inneror first portion 520-1 of the top shroud which comprises the inlet wall521 defining the periphery of the impeller inlet 522), and a portion ofthe bottom shroud 525 (i.e., an outer or first portion 525-1 of thebottom shroud). The second impeller portion 500-2 comprises a portion ofthe top shroud 520 (i.e., an outer or second portion 520-2 of the topshroud), the hub 530 structured for coupling to the rotor, a portion ofthe bottom shroud 525 (i.e., an inner or second portion 525-2 of thebottom shroud), and inner blade portions 513. The inner blade portions513 are adapted to be received in corresponding openings 514 providedwithin the impeller blades 510, e.g., to add rigidity to the impellerblades 510.

When the first impeller portion 500-1 is overmoulded to the secondimpeller portion 500-2 to produce the impeller 500, the inner portion520-1 and the outer portion 520-2 cooperate to form the top shroud 520,the outer portion 525-1 and the inner portion 525-2 cooperate to formthe bottom shroud 525, and the inner blade portions 513 add interiorrigidity to the impeller blades 510, i.e., inner blade portions 513 adda rigid material to the impeller blades 510. In such arrangement, theimpeller blades 510 and the leading and trailing edges 511, 512 thereofcomprise an elastomer material (e.g., silicone), and the hub 530comprises a rigid material for coupling to the rotor.

By such a construction, an impeller may be produced with the desired,advantageous aerodynamic features described herein, which can beinjection moulded. That is, using such a construction, the manufacturermay be able to withdraw a ‘core’ of the injecting moulding tool, as thefirst impeller portion 500-1 (e.g., comprising silicone) would be ableto resiliently deform to allow removal of the injection moulding tool.Further advantageously, such a material (e.g., silicone) of the firstimpeller portion 500-1 may allow manufacture of thinner wall sectionsthan plastic, thus enabling manufacture for example of the thin impellerblade leading edge 511 and/or trailing edge 512 described above.

Also, a strategic use of such a deformable, resilient material, ratherthan construction of an impeller entirely from a deformable, resilientmaterial, may help to manufacture an impeller wherein an overallstructural integrity is sufficient for durability as well as limitingdeformation in operation.

In other forms, an impeller may comprise multiple portions, each notnecessarily comprising different materials to each other.

In the example shown in FIGS. 19T-19X, the first impeller portion 500-1and the second impeller portion 500-2 may be separately moulded andassembled or fastened together. In an example, the first and secondportions may each comprise a rigid material (e.g., rigid plastic, suchas PEEK, also known as polyetheretherketone). In another example, thefirst portion may comprise a deformable, resilient material (e.g., anelastomeric material such as silicone) and the second portion maycomprise a rigid material (e.g., rigid plastic). For example, the firstportion 500-1 (i.e., the first moulded part or portion) may comprise thetop shroud 520, the impeller blades 510, and a first fastening portion550. The second portion 500-2 (i.e., the second moulded part or portion)may comprise the hub 530, the bottom shroud 525, and a second fasteningportion 555. The first impeller portion 500-1 and the second impellerportion 500-2 are fastened together by assembling the first fasteningportion 550 to the second fastening portion 555.

In the illustrated example, the first fastening portion 550 includes ahub portion 550-1 and radially extending projections 550-2 spaced aboutthe perimeter of the hub portion 550-1 (e.g., see FIG. 19W). The secondfastening portion 555 includes an annular slot 555-1 about the hub 530adapted to receive the hub portion 550-1 of the first fastening portion550 when assembled, and the second fastening portion 555 includesradially extending slots 555-2 adapted to receive respective projections550-2 of the first fastening portion 550 when assembled, e.g., toprevent relative rotation. However, it should be appreciated that thefirst and second fastening portions 550, 555 may comprise otherfastening configurations to fasten, interlock, or otherwise interfacethe first and second impeller portions.

The two portions 500-1 and 500-2 may be fastened or secured together toproduce the impeller 500, such as by snap fit, gluing, welding or anynumber of other suitable methods. Still further, in some forms, the twoportions 500-1 and 500-2 may be arranged such that coupling theassembled impeller 500 onto the motor (e.g., via motor shaft) furtherstrengthens the bonding between the portions of the impeller 500. Forexample, when the hub 530 of impeller 500 is coupled to the rotor ormotor shaft (e.g., by a press fit), the fastening (e.g., snap-fit)between the two portions 500-1 and 500-2 may be assisted and tightenedby such hub coupling, e.g., the snap-fit fastening may be tightened bythe press-fit coupling of the hub to the rotor.

It will of course be understood that this would not be limited toimpellers consisting of two portions, however any number of portions maybe assembled together to produce an impeller.

5.4.1.1.1.4.4 Exemplary Blower

FIG. 19FF shows a blower 600 for an RPT device including impellers 500according to one aspect of the present technology. In the illustratedexample, the blower 600 includes a two-stage design structured andconfigured for producing a flow, or a supply, of air at positivepressure, e.g., in the range of 4-30 cmH₂O. In an example, the RPTdevice is configured to deliver the flow of air from the outlet fordelivery to the patient at a pressure between 4-30 cmH₂O at an overallsound power level of less than 50 dB(A) thereby reducing any disturbanceto a quality of sleep for the patient. However, in alternative examples,the blower may include a single stage design, a three stage design, orfour or more stage designs.

As shown, the blower 600 includes a housing 610 including an axial airinlet (blower inlet) 612 and axial air outlet (blower outlet) 614between which are located two stages with corresponding impellers 500,i.e., a first impeller 500 positioned on one side of the motor 620 and asecond impeller 500 positioned on the other side of the motor 620. Themotor 620 includes a rotor 625 to which the impellers 500 are coupled.The impellers 500 are configured to be rotated by the rotor 625 todeliver a flow of air from the inlet 612 toward the outlet 614. However,other suitable impeller arrangements are possible. Each impeller 500 maybe followed by a set of stator vanes structured and configured to directthe air flow to the next stage or outlet.

In an example, the housing 610 may comprise a plurality of housingportions (e.g., first housing part including inlet 612, second housingpart including outlet 614, and intermediate housing parts (e.g.,stationary components providing stator vanes to direct air flow) thatare connected to one another (e.g., welded) to a form a substantiallysealed structure.

Further examples and details of the blower are described in PCT PatentApplication Publication No. WO 2013/020167, which is incorporated hereinby reference in its entirety.

According to one aspect of the present technology, a portion of thehousing 610 adjacent each impeller 500 may include a radius thatsubstantially corresponds to the radius at the leading edge 523 of theimpeller inlet wall 521 of the impeller 500. For example, as best shownon FIG. 19GG, a portion of the housing 610 adjacent the perimeter of theblower inlet 612 includes a generally curved surface, e.g., concavesurface 615, spaced from and adjacent the generally curved surface,e.g., convex surface 527, provided at the leading edge 523 of theimpeller inlet wall 521. In an example, such generally concave surface615 of the housing 610 includes a radius that substantially correspondsto a radius of the generally convex surface 527 provided at the leadingedge 523 of the impeller inlet wall 521.

The substantially corresponding radiuses, the configuration of thecurved channel 650 formed between the surfaces 615, 527 of the housing610 and the impeller 500, and such curved channel 650 terminating at apoint where the tangent would point generally downwards (i.e., towardsthe impeller as approximated by the short arrow A1 in FIG. 19GG) helpsre-circulated flow (indicated by the long arrow A2 in FIG. 19GG)smoothly enter the impeller inlet 522. That is, the curved channel 650formed by corresponding curved surfaces 615, 527 of the housing 610 andthe impeller 500 smoothly directs re-circulated flow into the impellerinlet 522.

5.4.1.1.1.5 Stators 4180, 4190

Like the impellers 4150, 4160, the blower 4142 may include multiplestators that correspond to each impeller. FIGS. 9A-9F and FIGS. 10A-10Edepict features of an example first stator 4180 that corresponds to thefirst impeller 4150, which together form the first compression stage4136. The first stator 4180 may include a plurality of first statorvanes 4187, 4188 to direct the flow of air from the first impeller 4150to a first stator opening 4186 in a radial direction, reduce thevelocity of the flow of air from the first impeller 4150, and increasethe pressure of the flow of air from the first impeller 4150.

The first stator vanes 4187, 4188 may be distinguished as extended firststator vanes 4187 and short first stator vanes 4188. The extended firststator vanes 4187 extend further radially inward than the short firststator vanes 4188, as can be seen in FIGS. 9D, 10C, and 10E. Theextended first stator vanes 4187 and the short first stator vanes 4188can also be seen alternating circumferentially around the first stator4180. The extended first stator vanes 4187 and the short first statorvanes 4188 may each include a curved portion 4181 that may be swept orcurved backwards relative to the direction of rotation 4139 of thecorresponding first impeller 4150. Alternatively, the curved portion4181 that may be swept or curved forwards relative to the direction ofrotation 4139 of the corresponding first impeller 4150. The curvedportion 4181 of each extended first stator vane 4187 and the curvedportion of each short first stator vane 4188 may shaped identically orthe curved portions 4181 may be shaped differently such that thedifferently shaped curved portions 4181 alternate circumferentiallyaround the first stator 4180. The extended first stator vanes 4187 andthe short first stator vanes 4188 may each comprise a straight portion4185 that extends radially inward from the curved portion 4181. Thestraight portion 4185 of each of the extended first stator vanes 4187may extend radially inward further than the straight portion 4185 ofeach of the short first stator vanes 4188, as can be seen in FIGS. 9D,10C, and 10E. The radially inward end of the extended first stator vanes4187 may be approximately 1.8 mm from the axis of rotation of the shaft4146. The radially inward end of the short first stator vanes 4188 maybe approximately 4.5 mm from the axis of rotation of the shaft 4146. Theradius of first stator vanes 4187, 4188, i.e., at the outermost point ofthe curved portion, may be 9.5 mm. The first stator 4180 may alsoinclude a shaft opening 4189 through which the shaft 4146 passes toreach the first impeller 4150.

Each first stator 4180 may also include a first stator opening 4186 thatis located downstream of the first stator vanes 4187, 4188 to direct theflow of air to the second impeller 4160. The first stator opening 4186may also be defined, at least in part, by a first stator lower shroud4182B. The first stator lower shroud 4182B may prevent the flow of gasfrom the first impeller 4150 from passing straight on to the secondimpeller 4160 in an axial direction by directing the flow of gasradially through the first stator vanes 4187 and then through the firststator opening 4186. Each first stator 4180 may also include a firststator upper shroud 4182A to direct the flow of air from the firstimpeller 4150 to the first stator opening 4186 in an axial direction bypreventing the flow of gas from flowing axially back to the underside ofthe first impeller shroud 4152. The corresponding first impeller 4150may also be positioned adjacent to the first stator upper shroud 4182A.

Each first stator 4180 may also include a first stator housing 4184that, at least in part, defines the flow path 4138. Each second impeller4160 and each second stator 4190 may be at least partially containedwithin the corresponding first stator housing 4184 such that the flow ofair travelling along the flow path 4138 past the second impeller 4160and through the second stator 4190 also passes through the first statorhousing 4184. In other words, the second compression stage 4137 may belocated within the first stator housing 4184. Accordingly, each firststator housing 4184 may at least partially define the correspondingblower outlet 4141.

Furthermore, each first stator housing 4184 may include a mountingstructure 4183 to connect the blower 4142 to the RPT system. In thedepicted examples, each mounting structure 4183 is in the form of a pairof mounting rails extending around the outer circumference of each firststator housing 4184. As described above, the lower housing portion 4133may be in the form of a clamshell that encloses the blower 4142 suchthat the mounting rails 4183 facilitate attachment to the plenum chamber3200, as shown in FIG. 6B.

As explained above, each second compression stage 4137 may be containedwithin the corresponding first stator housing 4184 and each such secondcompression stage 4137 may be comprised of a second impeller 4160(described above) and a second stator 4190. The second stator 4190 mayinclude a top ring 4192, a base ring 4194, and a plurality of secondstator vanes 4191 between the top ring 4192 and the base ring 4194. Thesecond stator vanes 4191 may direct the flow of air from the secondimpeller 4160 to the blower outlet 4141 in a radial and axial direction,reduce the velocity of the flow of air from the second impeller 4160,and increase the pressure of the flow of air from the second impeller4160. Each of the second stator vanes may have a constant depth D in aradial direction and an increasing width W in a circumferentialdirection from the top ring 4192 to the base ring 4194, as shown inFIGS. 11A and 11B.

The top ring 4192 may also include a top ring recess 4195 and the basering 4194 includes a base ring recess 4196. The top ring recess 4195 andthe base ring recess 4196 allow a flexible printed circuit boardassembly (PCBA) to pass therethrough to provide power and controlsignals to the motor 4145. As can be seen in FIGS. 6B, 7E, and 10A themotor 4145 is also contained, at least partially, within the secondstator 4190. Thus, the motor 4145 may partially define an internalboundary of the flow path 4138.

The second stator 4190 may also at least partially define the bloweroutlet 4141. Second stator outlet ribs 4193 can be seen in FIGS. 11A-11Cjoining corresponding second stator vanes 4191 to the base ring 4194.Thus, once the flow of gas has passed through the second stator vanes4191, the flow of air is then directed out of the blower 4142 and intothe plenum chamber 3200 through the blower outlet 4141 and between thesecond stator outlet ribs 4193. As can be seen in FIG. 6B, for example,the blower outlet 4141 may be located near the center of the blower 4142in the axial direction.

5.4.1.1.1.6 End Caps 4144

At each axial end of the blower 4142, an end cap 4144 may also beprovided to enclose the first compression stage 4136, including thefirst impeller 4150 and at least a portion of the first stator 4180. Theend cap 4144 may at least partially define the blower inlet 4143 foreach axial end of the blower 4142. In other words, the flow of air forthe first compression stage 4136 may be drawn in through the blowerinlet 4143 defined by the end cap 4144. Each end cap 4144 may beconstructed to reduce noise and/or vibration. Each end cap 4144 may beformed from a rigid material to provide structural integrity and a lessrigid, elastically deformable material overmolded to the rigid materialto reduce noise and/or vibration. Other housing structures of the blower4142, e.g., the first stator housing 4184, may also be formed from asimilar construction to mitigate noise and vibration, since these arethe most external components of the blower 4142. The end cap 4144 mayalso be integrated with the blower's 4142 housing structures, e.g., thefirst stator housing 4184, in one piece of homogeneous material or withthe plenum chamber's 3200 housing structures, e.g., the lower housingportion 4133. Alternatively, the end cap 4144 may be mounted to thelower housing portion 4133 such that it is isolated from the blower4142. Membranes or other flexible structures may be provided between theend cap 4144 and the other blower components to absorb noise andvibration.

Alternatively, to the passive noise mitigation measures described above,incorporating active noise cancelation features into the blower 4142 orelsewhere in the plenum chamber 3200 is also possible, suchincorporating microphones in the RPT device.

5.4.1.1.1.7 Single Stage Pressure Generator

FIG. 14 depicts another example of the blower 4142 according to thepresent technology that includes a single stage of compression on eachside of the motor 4145. The motor 4145 may have a single shaft 4146protruding from each end thereof to drive corresponding impellers 4160.The impellers 4160 may each be associated with a stator 4190 on eachside of the motor 4145. The blower 4142 may also have a housing 4148 oneach side with a blower inlet 4143 and a mounting structure 4183 tosecure the blower 4142 to the plenum chamber 3200. Each housing 4148 mayenclose the corresponding impeller 4160 and the corresponding stator4190. The impellers 4160 and the stators 4190 of this example mayinclude any of the features described with respect to the examplesabove. While it may be necessary for the motor 4145 of this example tooperate at a higher speed to generate flow rates and pressurescomparable to the dual-stage examples described above, this single stagevariation may provide a lighter and more compact design that is lessobtrusive and lighter for the patient.

5.4.1.2 Transducer(s)

Transducers may be internal of the RPT device, or external of the RPTdevice. External transducers may be located for example on or form partof the air circuit, e.g., the patient interface. External transducersmay be in the form of non-contact sensors such as a Doppler radarmovement sensor that transmit or transfer data to the RPT device.

In one form of the present technology, one or more transducers 4270 arelocated upstream and/or downstream of the pressure generator 4140, suchas one or more of those listed above. The one or more transducers 4270may be constructed and arranged to generate signals representingproperties of the flow of air such as a flow rate, a pressure, or atemperature at that point in the pneumatic path.

5.4.1.2.1 Flow Rate Sensor

A flow rate sensor 4274 in accordance with the present technology may bebased on a differential pressure transducer, for example, an SDP600Series differential pressure transducer from SENSIRION.

5.4.1.2.2 Pressure Sensor

A pressure sensor 4272 in accordance with the present technology islocated in fluid communication with the pneumatic path. An example of asuitable pressure sensor is a transducer from the HONEYWELL ASDX series.An alternative suitable pressure sensor is a transducer from the NPASeries from GENERAL ELECTRIC.

5.4.1.2.3 Motor Speed Transducer

In one form of the present technology a motor speed transducer 4276 isused to determine a rotational velocity of the motor 4145 and/or theblower 4142.

5.4.2 RPT Device Electrical Components

5.4.2.1 Power Supply

A power supply 4210 may be located internally or externally of theexternal housing 4010 of the RPT device 4000.

In the exemplary RPT system of FIGS. 6A-6C, the power supply 4210 may bein the form of a battery that has at least one electrochemical cell. Thepower supply 4210 in the form of a battery may be supported by thepositioning and stabilising structure 3300 on a region of the patient'shead adjacent to the parietal bone. The power supply 4210 in the form ofa battery may also be contained within the positioning and stabilisingstructure 3300. In other words, the power supply 4210 in the form of abattery may be at least partially enclosed by the materials of thepositioning and stabilising structure 3300. If the power supply 4210 inthe form of a battery is completely enclosed by the positioning andstabilising structure 3300, then the positioning and stabilisingstructure 3300 may include an opening to provide access to the powersupply 4210 and the opening may be closed with hook-and-loopfastener(s), button(s), snap(s), etc.

In the example of the power supply 4210 in the form of a battery, thebattery may be shaped to generally conform to the shape of thecorresponding portion of the patient's head. By shaping the batterythis, the power supply 4210 may maintain a relatively low profile thatis minimally obtrusive to the patient. The positioning and stabilisingstructure 3300 may also include mounting point(s) for add-on featuresfor the power supply 4210, e.g., a supplemental battery.

5.4.2.2 Input Devices

In one form of the present technology, an RPT device 4000 includes oneor more input devices 4220 in the form of buttons, switches or dials toallow a person to interact with the device. The buttons, switches ordials may be physical devices, or software devices accessible via atouch screen. The buttons, switches or dials may, in one form, bephysically connected to the external housing 4010, or may, in anotherform, be in wireless communication with a receiver that is in electricalconnection to the central controller 4230.

In the example of the present technology depicted in FIGS. 6A-6C, one ormore input devices 4220, such as those described above, may be providedto the upper housing portion 4132 or the lower housing portion 4133 ofthe plenum chamber or to the positioning and stabilising structure 3300.

5.4.2.3 Central Controller

In one form of the present technology, the central controller 4230 isone or a plurality of processors suitable to control an RPT device 4000.

In some forms of the present technology, the central controller 4230 isconfigured to implement the one or more methodologies described herein,such as the one or more algorithms expressed as computer programs storedin a non-transitory computer readable storage medium, such as memory4260. In some forms of the present technology, the central controller4230 may be integrated with an RPT device 4000. However, in some formsof the present technology, some methodologies may be performed by aremotely located device. For example, the remotely located device maydetermine control settings for a ventilator or detect respiratoryrelated events by analysis of stored data such as from any of thesensors described herein.

In the example depicted in FIGS. 6A-6C, the RPT system may include acontrol system to control the blower 4142 and the control system mayinclude one or more of the features described in the precedingparagraphs of this section. The control system may include a flexibleprinted circuit board assembly (PCBA) that comprises a microprocessor,such as those described above. The microprocessor is may be programmedto perform at least one of closed-loop pressure control based on sensedpressure data, flow rate estimation, and automatically adjustingexpiration pressure relief. The control system may also a drive circuitto control the power supply 4210 separately from the blower 4142.

5.4.2.4 Memory

In accordance with one form of the present technology the RPT device4000 includes memory 4260, e.g., non-volatile memory. In some forms,memory 4260 may include battery powered static RAM. In some forms,memory 4260 may include volatile RAM.

Memory 4260 may be located on the PCBA 4202. Memory 4260 may be in theform of EEPROM, or NAND flash.

Additionally or alternatively, RPT device 4000 includes a removable formof memory 4260, for example a memory card made in accordance with theSecure Digital (SD) standard.

In one form of the present technology, the memory 4260 acts as anon-transitory computer readable storage medium on which is storedcomputer program instructions expressing the one or more methodologiesdescribed herein, such as the one or more algorithms.

5.4.2.5 Data Communication Systems

In one form of the present technology, a data communication interface4280 is provided, and is connected to the central controller 4230. Datacommunication interface 4280 may be connectable to a remote externalcommunication network 4282 and/or a local external communication network4284. The remote external communication network 4282 may be connectableto a remote external device 4286. The local external communicationnetwork 4284 may be connectable to a local external device 4288.

In one form, data communication interface 4280 is part of the centralcontroller 4230. In another form, data communication interface 4280 isseparate from the central controller 4230, and may comprise anintegrated circuit or a processor.

In one form, the remote external communication network 4282 is theInternet. The data communication interface 4280 may use wiredcommunication (e.g. via Ethernet, or optical fibre) or a wirelessprotocol (e.g. CDMA, GSM, LTE) to connect to the Internet.

In one form, the local external communication network 4284 utilises oneor more communication standards, such as Bluetooth, or a consumerinfrared protocol.

In one form, the remote external device 4286 is one or more computers,for example a cluster of networked computers. In one form, remote theexternal device 4286 may be virtual computers, rather than physicalcomputers. In either case, such a remote external device 4286 may beaccessible to an appropriately authorised person such as a clinician.

The local external device 4288 may be a personal computer, mobile phone,tablet or remote control.

5.4.3 RPT Device Algorithms

As mentioned above, in some forms of the present technology, the centralcontroller 4230 may be configured to implement one or more algorithmsexpressed as computer programs stored in a non-transitory computerreadable storage medium, such as memory 4260. The algorithms aregenerally grouped into groups referred to as modules.

5.4.4 Oxygen Delivery

In one form of the present technology, supplemental oxygen 4001 isdelivered to one or more points in the pneumatic path, such as upstreamof the pneumatic block 4020, to the air circuit 4170 and/or to thepatient interface 3000.

5.5 Glossary

For the purposes of the present technology disclosure, in certain formsof the present technology, one or more of the following definitions mayapply. In other forms of the present technology, alternative definitionsmay apply.

5.5.1 General

Air: In certain forms of the present technology, air may be taken tomean atmospheric air, and in other forms of the present technology airmay be taken to mean some other combination of breathable gases, e.g.atmospheric air enriched with oxygen.

Ambient: In certain forms of the present technology, the term ambientwill be taken to mean (i) external of the treatment system or patient,and (ii) immediately surrounding the treatment system or patient.

For example, ambient humidity with respect to a humidifier may be thehumidity of air immediately surrounding the humidifier, e.g. thehumidity in the room where a patient is sleeping. Such ambient humiditymay be different to the humidity outside the room where a patient issleeping.

In another example, ambient pressure may be the pressure immediatelysurrounding or external to the body.

In certain forms, ambient (e.g., acoustic) noise may be considered to bethe background noise level in the room where a patient is located, otherthan for example, noise generated by an RPT device or emanating from amask or patient interface. Ambient noise may be generated by sourcesoutside the room.

Automatic Positive Airway Pressure (APAP) therapy: CPAP therapy in whichthe treatment pressure is automatically adjustable, e.g. from breath tobreath, between minimum and maximum limits, depending on the presence orabsence of indications of SDB events.

Continuous Positive Airway Pressure (CPAP) therapy: Respiratory pressuretherapy in which the treatment pressure is approximately constantthrough a respiratory cycle of a patient. In some forms, the pressure atthe entrance to the airways will be slightly higher during exhalation,and slightly lower during inhalation. In some forms, the pressure willvary between different respiratory cycles of the patient, for example,being increased in response to detection of indications of partial upperairway obstruction, and decreased in the absence of indications ofpartial upper airway obstruction.

Flow rate: The volume (or mass) of air delivered per unit time. Flowrate may refer to an instantaneous quantity. In some cases, a referenceto flow rate will be a reference to a scalar quantity, namely a quantityhaving magnitude only. In other cases, a reference to flow rate will bea reference to a vector quantity, namely a quantity having bothmagnitude and direction. Flow rate may be given the symbol Q. ‘Flowrate’ is sometimes shortened to simply ‘flow’ or ‘airflow’.

Humidifier: The word humidifier will be taken to mean a humidifyingapparatus constructed and arranged, or configured with a physicalstructure to be capable of providing a therapeutically beneficial amountof water (H₂O) vapour to a flow of air to ameliorate a medicalrespiratory condition of a patient.

Leak: The word leak will be taken to be an unintended flow of air. Inone example, leak may occur as the result of an incomplete seal betweena mask and a patient's face. In another example leak may occur in aswivel elbow to the ambient.

Patient: A person, whether or not they are suffering from a respiratorycondition.

Pressure: Force per unit area. Pressure may be expressed in a range ofunits, including cmH₂O, g-f/cm² and hectopascal. 1 cmH₂O is equal to 1g-f/cm² and is approximately 0.98 hectopascal. In this specification,unless otherwise stated, pressure is given in units of cmH₂O.

Respiratory Pressure Therapy (RPT): The application of a supply of airto an entrance to the airways at a treatment pressure that is typicallypositive with respect to atmosphere.

5.5.1.1 Materials

Silicone or Silicone Elastomer: A synthetic rubber. In thisspecification, a reference to silicone is a reference to liquid siliconerubber (LSR) or a compression moulded silicone rubber (CMSR). One formof commercially available LSR is SILASTIC (included in the range ofproducts sold under this trademark), manufactured by Dow Corning.Another manufacturer of LSR is Wacker. Unless otherwise specified to thecontrary, an exemplary form of LSR has a Shore A (or Type A) indentationhardness in the range of about 35 to about 45 as measured using ASTMD2240.

Polycarbonate: a thermoplastic polymer of Bisphenol-A Carbonate.

5.5.1.2 Mechanical Properties

Resilience: Ability of a material to absorb energy when deformedelastically and to release the energy upon unloading.

Resilient: Will release substantially all of the energy when unloaded.Includes e.g. certain silicones, and thermoplastic elastomers.

Hardness: The ability of a material per se to resist deformation (e.g.described by a Young's Modulus, or an indentation hardness scalemeasured on a standardised sample size).

-   -   ‘Soft’ materials may include silicone or thermo-plastic        elastomer (TPE), and may, e.g. readily deform under finger        pressure.    -   ‘Hard’ materials may include polycarbonate, polypropylene, steel        or aluminium, and may not e.g. readily deform under finger        pressure.

Stiffness (or rigidity) of a structure or component: The ability of thestructure or component to resist deformation in response to an appliedload. The load may be a force or a moment, e.g. compression, tension,bending or torsion. The structure or component may offer differentresistances in different directions.

Floppy structure or component: A structure or component that will changeshape, e.g. bend, when caused to support its own weight, within arelatively short period of time such as 1 second.

Rigid structure or component: A structure or component that will notsubstantially change shape when subject to the loads typicallyencountered in use. An example of such a use may be setting up andmaintaining a patient interface in sealing relationship with an entranceto a patient's airways, e.g. at a load of approximately 20 to 30 cmH₂Opressure.

As an example, an I-beam may comprise a different bending stiffness(resistance to a bending load) in a first direction in comparison to asecond, orthogonal direction. In another example, a structure orcomponent may be floppy in a first direction and rigid in a seconddirection.

5.5.2 Respiratory Cycle

Apnea: According to some definitions, an apnea is said to have occurredwhen flow falls below a predetermined threshold for a duration, e.g. 10seconds. An obstructive apnea will be said to have occurred when,despite patient effort, some obstruction of the airway does not allowair to flow. A central apnea will be said to have occurred when an apneais detected that is due to a reduction in breathing effort, or theabsence of breathing effort, despite the airway being patent. A mixedapnea occurs when a reduction or absence of breathing effort coincideswith an obstructed airway.

Expiratory portion of a breathing cycle: The period from the start ofexpiratory flow to the start of inspiratory flow.

Inspiratory portion of a breathing cycle: The period from the start ofinspiratory flow to the start of expiratory flow will be taken to be theinspiratory portion of a breathing cycle.

5.5.3 Anatomy

5.5.3.1 Anatomy of the Face

Nares (Nostrils): Approximately ellipsoidal apertures forming theentrance to the nasal cavity. The singular form of nares is naris(nostril). The nares are separated by the nasal septum.

Otobasion inferior: The lowest point of attachment of the auricle to theskin of the face.

Otobasion superior: The highest point of attachment of the auricle tothe skin of the face.

Sagittal plane: A vertical plane that passes from anterior (front) toposterior (rear) dividing the body into right and left halves.

5.5.3.2 Anatomy of the Skull

Occipital bone: The occipital bone is situated at the back and lowerpart of the cranium. It includes an oval aperture, the foramen magnum,through which the cranial cavity communicates with the vertebral canal.The curved plate behind the foramen magnum is the squama occipitalis.

Parietal bones: The parietal bones are the bones that, when joinedtogether, form the roof and sides of the cranium.

5.5.3.3 Anatomy of the Respiratory System

Nasal cavity: The nasal cavity (or nasal fossa) is a large air filledspace above and behind the nose in the middle of the face. The nasalcavity is divided in two by a vertical fin called the nasal septum. Onthe sides of the nasal cavity are three horizontal outgrowths callednasal conchae (singular “concha”) or turbinates. To the front of thenasal cavity is the nose, while the back blends, via the choanae, intothe nasopharynx.

5.5.4 Patient Interface

Anti-asphyxia valve (AAV): The component or sub-assembly of a masksystem that, by opening to atmosphere in a failsafe manner, reduces therisk of excessive CO₂ rebreathing by a patient.

Headgear: Headgear will be taken to mean a form of positioning andstabilizing structure designed for use on a head. For example theheadgear may comprise a collection of one or more struts, ties andstiffeners configured to locate and retain a patient interface inposition on a patient's face for delivery of respiratory therapy. Someties are formed of a soft, flexible, elastic material such as alaminated composite of foam and fabric.

Membrane: Membrane will be taken to mean a typically thin element thathas, preferably, substantially no resistance to bending, but hasresistance to being stretched.

Plenum chamber: a mask plenum chamber will be taken to mean a portion ofa patient interface having walls at least partially enclosing a volumeof space, the volume having air therein pressurised above atmosphericpressure in use. A shell may form part of the walls of a mask plenumchamber.

Seal: May be a noun form (“a seal”) which refers to a structure, or averb form (“to seal”) which refers to the effect. Two elements may beconstructed and/or arranged to ‘seal’ or to effect ‘sealing’therebetween without requiring a separate ‘seal’ element per se.

Stiffener: A stiffener will be taken to mean a structural componentdesigned to increase the bending resistance of another component in atleast one direction.

Strut: A strut will be taken to be a structural component designed toincrease the compression resistance of another component in at least onedirection.

Tie (noun): A structure designed to resist tension.

Vent: (noun): A structure that allows a flow of air from an interior ofthe mask, or conduit, to ambient air for clinically effective washout ofexhaled gases. For example, a clinically effective washout may involve aflow rate of about 10 litres per minute to about 100 litres per minute,depending on the mask design and treatment pressure.

5.6 Other Remarks

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in Patent Office patent files orrecords, but otherwise reserves all copyright rights whatsoever.

Unless the context clearly dictates otherwise and where a range ofvalues is provided, it is understood that each intervening value, to thetenth of the unit of the lower limit, between the upper and lower limitof that range, and any other stated or intervening value in that statedrange is encompassed within the technology. The upper and lower limitsof these intervening ranges, which may be independently included in theintervening ranges, are also encompassed within the technology, subjectto any specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the technology.

Furthermore, where a value or values are stated herein as beingimplemented as part of the technology, it is understood that such valuesmay be approximated, unless otherwise stated, and such values may beutilized to any suitable significant digit to the extent that apractical technical implementation may permit or require it.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this technology belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present technology, a limitednumber of the exemplary methods and materials are described herein.

When a particular material is identified as being used to construct acomponent, obvious alternative materials with similar properties may beused as a substitute. Furthermore, unless specified to the contrary, anyand all components herein described are understood to be capable ofbeing manufactured and, as such, may be manufactured together orseparately.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include their plural equivalents,unless the context clearly dictates otherwise.

All publications mentioned herein are incorporated herein by referencein their entirety to disclose and describe the methods and/or materialswhich are the subject of those publications. The publications discussedherein are provided solely for their disclosure prior to the filing dateof the present application. Nothing herein is to be construed as anadmission that the present technology is not entitled to antedate suchpublication by virtue of prior invention. Further, the dates ofpublication provided may be different from the actual publication dates,which may need to be independently confirmed.

The terms “comprises” and “comprising” should be interpreted asreferring to elements, components, or steps in a non-exclusive manner,indicating that the referenced elements, components, or steps may bepresent, or utilized, or combined with other elements, components, orsteps that are not expressly referenced.

The subject headings used in the detailed description are included onlyfor the ease of reference of the reader and should not be used to limitthe subject matter found throughout the disclosure or the claims. Thesubject headings should not be used in construing the scope of theclaims or the claim limitations.

Although the technology herein has been described with reference toparticular examples, it is to be understood that these examples aremerely illustrative of the principles and applications of thetechnology. In some instances, the terminology and symbols may implyspecific details that are not required to practice the technology. Forexample, although the terms “first” and “second” may be used, unlessotherwise specified, they are not intended to indicate any order but maybe utilised to distinguish between distinct elements. Furthermore,although process steps in the methodologies may be described orillustrated in an order, such an ordering is not required. Those skilledin the art will recognize that such ordering may be modified and/oraspects thereof may be conducted concurrently or even synchronously.

It is therefore to be understood that numerous modifications may be madeto the illustrative examples and that other arrangements may be devisedwithout departing from the spirit and scope of the technology.

REFERENCE SIGNS LIST plane curve   301D surface   302D impeller  500first impeller portion   500-1 second impeller portion   500-2 impellerblade  510 impeller blade leading edge  511 impeller blade trailing edge 512 inner blade portion  513 opening  514 first edge  515 second edge 517 curved surface  519 top shroud  520 top shroud first portion  520-1 top shroud second portion   520-2 inlet wall  521 impeller inlet 522 leading edge  523 impeller outlet  524 bottom shroud  525 bottomshroud first portion   525-1 bottom shroud second portion   525-2 curvedsurface  527 hub  530 flow passage  540 first fastening portion  550 hubportion   550-1 projection   550-2 second fastening portion  555 annularslot   555-1 slot   555-2 blower  600 housing  610 blower inlet  612blower outlet  614 curved surface  615 motor  620 rotor  625 channel 650 patient 1000 sleeping patient 1000 bed partner 1100 headbox 2000ground electrode ISOG 2010 respiratory inductance plethysmogram 2040respiratory inductance plethysmogram 2045 oro - nasal cannula 2050 bodyposition sensor 2060 patient interface 3000 seal - forming structure3100 plenum chamber 3200 perimeter 3210 marginal edge 3220 positioningand stabilising structure 3300 wire 3301 tube 3302 lateral portion ofthe tie 3303 superior portion of the tie 3304 posterior portion of thetie 3305 tab 3306 wire retainer 3307 adjustment mechanism 3308 ventassembly 3400 exterior vent hole surface 3401 vent hole 3402 vent holeextension 3403 base 3404 flexible membrane 3405 divider 3406 interiorvent hole surface 3407 internal surface 3408 vent flow 3409 pressurizedflow 3410 connection port 3600 forehead support 3700 RPT Device 4000supplementary oxygen 4001 external housing 4010 upper portion 4012 lowerportion 4014 panel 4015 chassis 4016 handle 4018 pneumatic block 4020pneumatic component 4100 air filter 4110 inlet air filter 4112 outletair filter 4114 muffler 4120 inlet muffler 4122 outlet muffler 4124attachment structure 4130 plenum chamber outlet 4131 upper housingportion 4132 lower housing portion 4133 pressure port 4134 heat andmoisture exchanger (HME) retention structure 4135 first compressionstage 4136 second compression stage 4137 flow path 4138 direction ofrotation 4139 pressure generator 4140 blower outlet 4141 blower 4142blower inlet 4143 end cap 4144 motor 4145 shaft 4146 housing 4148 firstimpeller 4150 first impeller vanes 4151 first impeller shroud 4152 firstimpeller hub 4153 first impeller vane portion 4154 second impeller vaneportion 4155 first impeller shroud portion 4156 second impeller shroudportion 4157 second impeller 4160 air circuit 4170 heated air circuit4171 first stator 4180 curved portion 4181 first stator upper shroud  4182A first stator lower shroud   4182B mounting rails 4183 firststator housing 4184 straight portion 4185 first stator opening 4186extended first stator vanes 4187 short first stator vanes 4188 shaftopening 4189 second stator 4190 second stator vanes 4191 top ring 4192second stator outlet rib 4193 base ring 4194 top ring recess 4195 basering recess 4196 electrical component 4200 printed circuit boardassembly 4202 power supply 4210 input device 4220 central controller4230 retainer 4231 clock 4232 therapy device controller 4240 protectioncircuit 4250 memory 4260 transducer 4270 pressure sensor 4272 flow ratesensor 4274 motor speed transducer 4276 data communication interface4280 remote external communication network 4282 local externalcommunication network 4284 remote external device 4286 local externaldevice 4288 output device 4290 display driver 4292 display 4294 method4500 step 4520 step 4530 step 4540 step 4550 step 4560 humidifier 5000humidifier inlet 5002 humidifier outlet 5004 humidifier base 5006 waterreservoir 5110 humidifier reservoir 5110 conductive portion 5120humidifier reservoir dock 5130 locking lever 5135 water level indicator5150 humidifier transducer 5210 pressure transducer 5212 flow ratetransducer 5214 temperature transducer 5216 humidity sensor 5218 heatingelement 5240 humidifier controller 5250 central humidifier controller5251 heating element controller 5252 air circuit controller 5254monitoring apparatus 7100

1-76. (canceled)
 77. A respiratory pressure therapy (RPT) systemcomprising: at least one housing portion at least partially defining aplenum chamber pressurisable to a therapeutic pressure of at least 6cmH₂O above ambient air pressure; a seal-forming structure constructedand arranged to form a seal with a region of the patient's face at orsurrounding an entrance to the patient's airways such that a flow of airat said therapeutic pressure is delivered to at least the entrance tothe patient's nares, the seal-forming structure constructed and arrangedto maintain said therapeutic pressure in the plenum chamber throughoutthe patient's respiratory cycle in use; a positioning and stabilisingstructure constructed and arranged to provide an elastic force to holdthe seal-forming structure in a therapeutically effective position onthe patient's head, the positioning and stabilising structure comprisinga tie, a lateral portion of the tie being constructed and arranged tooverlie a region of the patient's head superior to the otobasionsuperior in use, and a superior portion of the tie being constructed andarranged to overlie a region of the patient's head in a region of theparietal bone in use, wherein the positioning and stabilising structurehas a non-rigid decoupling portion; a blower configured to generate theflow of air and pressurise the plenum chamber to the therapeuticpressure, the blower having a motor, the blower being connected to theplenum chamber such that in use the blower is suspended from thepatient's head and an axis of rotation of the motor is generallyperpendicular to the patient's sagittal plane; and a power supplyconfigured to provide electrical power to the blower, wherein the atleast one housing portion comprises a vent assembly, the vent assemblycomprising: a base having a first side and a second side and a passagethrough the base from the first side to the second side, the passageconfigured to allow a pressurized flow of gas through the base from thefirst side to the second side; at least one vent hole extensionextending from the base and at least partially defining the passage; atleast one vent hole passing through the at least one vent holeextension, the at least one vent hole configured to allow a vent flow ofgas to pass from the passage to atmosphere; and at least one flexiblemembrane attached to the at least one vent hole extension and extendinginto the passage, the at least one flexible membrane being configured tocover the at least one vent hole in a closed position to prevent thepressurized flow of gas from being discharged from the passage toatmosphere, and the at least one flexible membrane being configured notto cover the at least one vent hole in an open position to allow thevent flow of gas to be discharged to atmosphere from the passage. 78.The RPT system of claim 77, wherein the at least one vent hole extensionincludes an interior vent hole surface, each at least one vent holepassing through the interior vent hole surface to the passage.
 79. TheRPT system of claim 78, wherein the at least one flexible membrane isattached to the at least one vent hole extension at the interior venthole surface.
 80. The RPT system of claim 79, wherein the at least onevent hole extension includes an exterior vent hole surface, each atleast one vent hole passing through the exterior vent hole surface toatmosphere.
 81. The RPT system of claim 80, wherein the at least onevent hole extension further comprises an internal surface, and whereinthe vent hole extension has a generally triangular cross-section formedby the interior vent hole surface, the exterior vent hole surface, andthe internal surface.
 82. The RPT system of claim 78, wherein theinterior vent hole surface slopes downwardly into the interior of thevent assembly relative to the flow of pressurized gas passing throughthe passage.
 83. The RPT system of claim 77, wherein the at least onevent hole extension further comprises two diametrically opposed venthole extensions, wherein the at least one flexible membrane furthercomprises two flexible membranes, each of the two flexible membranesattached to a corresponding one of the two diametrically opposed venthole extensions, and wherein the vent assembly further comprises adivider positioned between the two diametrically opposed vent holeextensions to form a first passage and a second passage.
 84. The RPTsystem of claim 83, wherein the two flexible membranes do not contactthe divider in the open position.
 85. The RPT system of claim 77,wherein the at least one flexible membrane is constructed of anelastically deformable material.
 86. The RPT system of claim 77, whereinthe at least one flexible membrane is cantilevered to the at least onevent hole extension.
 87. The RPT system of claim 77, wherein the bloweris contained at least partially within the plenum chamber.
 88. The RPTsystem of claim 87, wherein the plenum chamber comprises at least onehousing portion.
 89. The RPT system of claim 88, wherein the plenumchamber comprises at least two housing portions that are at leastpartially separable to allow the blower to be removed from the plenumchamber.
 90. The RPT system of claim 89, wherein the at least twohousing portions are joined at one side in a clamshell arrangement toallow the plenum chamber to be opened and closed.
 91. The RPT system ofclaim 90, further comprising a sealing structure between the at leasttwo housing portions.
 92. The RPT system of claim 77, wherein the plenumchamber includes at least one attachment structure to attach thepositioning and stabilising structure to secure the RPT system to thepatient's head in use.
 93. The RPT system of claim 77, wherein theplenum chamber comprises a port that is configured to be connected to atleast one of a pressure transducer and a supplemental gas source. 94.The RPT system of claim 77, wherein the seal-forming structurecomprises: a pair of nasal puffs, or nasal pillows, each nasal puff ornasal pillow being constructed and arranged to form a seal with arespective naris of the nose of the patient; a seal-forming structurethat forms a seal in use on a nose bridge region or on a nose-ridgeregion of the patient's face and that forms a seal in use on an upperlip region of the patient's face; or a seal-forming structure that formsa seal in use on a nose bridge region or on a nose-ridge region of thepatient's face and that forms a seal in use on a chin-region of thepatient's face.
 95. The RPT system of claim 77, further comprising aheat and moisture exchanger (HME) within the plenum chamber that ispositioned in the flow of air and downstream of the blower.
 96. The RPTsystem of claim 77, wherein the power supply comprises a battery, thebattery further comprising at least one electrochemical cell.
 97. TheRPT system of claim 96, further comprising at least one wire supportedby the positioning and stabilising structure, the at least one wireproviding electrical communication between the blower and the battery.98. The RPT system of claim 97, wherein the at least one wire iscontained within the lateral portion of the positioning and stabilisingstructure.
 99. The RPT system of claim 77, wherein the seal-formingstructure comprises an elastically deformable material that is lessrigid than the plenum chamber, and wherein a portion of the seal-formingstructure substantially encloses the plenum chamber and the blower whileallowing at least an inlet of the blower to remain exposed.
 100. The RPTsystem of claim 99, wherein the seal-forming structure is shaped anddimensioned and the elastically deformable material of the seal-formingstructure is selected to at least partially isolate the patient's headfrom vibration and dampen sound generated by the blower in use.
 101. TheRPT system of claim 77, further comprising a cover comprising anelastically deformable material that is less rigid than the plenumchamber that substantially encloses the plenum chamber and the blowerwhile allowing at least an inlet of the blower to remain exposed. 102.The RPT system of claim 101, wherein the cover is shaped and dimensionedand the elastically deformable material of the cover is selected to atleast partially isolate the patient's head from vibration and dampensound generated by the blower in use.
 103. The RPT system of claim 77,further comprising a control system to control the blower in use. 104.The RPT system of claim 103, wherein the control system comprises aflexible printed circuit board assembly (PCBA), the PCBA comprising amicroprocessor.
 105. The RPT system of claim 104, wherein themicroprocessor is programmed to perform at least one of closed-looppressure control based on sensed pressure data, flow rate estimation,and automatically adjusting expiration pressure relief.
 106. The RPTsystem of claim 105, wherein the control system further comprises adrive circuit to control the power supply separately from the blower.